WHEN Rhona Cameron was 18 she won a conditional place at Edinburgh College of Art. The day in 1983 that she received the news is branded like an indelible, unsightly tattoo on her forehead because she knew immediately that she would not be able to take it up. Why? Because, she says, there was never any chance of her acquiring the additional qualifications necessary to be accepted.

"It broke my heart," she says. "It ruined my young adult life and contributed to my wasted 30s. I would have got out of Musselburgh at that time and I would have been with some like-minded people. I would have been in a cultured environment. It would have been better for my sexuality. I would have been in a mixed environment, instead of, you know, the anti-sexist, anti-nuclear, feminist movement, which was the only way to get laid at the time. I would have had healthier relationships with men. I would probably have gone and joined the drama group. I would have travelled around Europe. I'd have done all that. Instead, I ended up living like one of the cast of Trainspotting."

Cameron, who is 41, is a compulsive, addictive talker. Words pour from her mouth like water from the Trevi fountain. She is dressed in jeans and has her hair cropped short. Her face is youthful and unlined and flushed from cycling from her rented home to the Café Mozart not a million miles from Karl Marx's resting place in north London. She has an air of agitated restlessness, exacerbated today because it is the deadline for the Edinburgh Fringe programme and she is still trying to decide whether to join the madding August crowds. There is a play in gestation and the possibility of reviving her stand-up career.

On top of which she has an urgent call to make to an estate agent and the desperate need for coffee and breakfast. Were one a teacher one would tell her to sit down, take a deep breath and concentrate on doing one thing at a time. That, though, as Cameron would readily acknowledge, is not something she is good at. She has always, she says, been the kind of person who juggles lots of different projects, partly in order to make a living, partly because her talents are so diverse. It is, it seems, a characteristic of stand-ups who, having never been trained, come to believe that they can accomplish whatever they set out to achieve. The way Cameron describes it, one might think they are to the present age what Leonardo was to the Renaissance. "I like the fact that stand-ups have taught themselves," she says. "It's hard to tell us we can't do things."

Cameron's CV is testament to that. In 1992, she won Channel 4's So You Think You're Funny award, after which she performed for a decade on the Fringe and toured around Britain and the Antipodes. She has made countless guest appearances on prime-time TV shows, written four series of BBC2's Gaytime TV and co-written and starred in the eponymous sitcom Rhona. In 2002 she was plucked from the gay ghetto and despatched to the Australian jungle where she was marooned with the likes of Christine Hamilton, Nigel Benn and Tara Palmer-Tomkinson for the first series of I'm A Celebrity ... Get Me Out of Here! which, in hindsight, could be a fitting epitaph for her, given her loathing of the celebrity culture. "Who's f***ing who?" she groans. "Who's having a baby? Who's in rehab? I hate all that shit."

In 2003, she published her first book. Nineteen Seventy-Nine, subtitled A Big Year In A Small Town, namely Musselburgh, where coincidentally both Cameron and I are from. Of late, apparently, property prices in the Honest Toun have been rising faster than anywhere else in the country. Whatever else Cameron has achieved, she cannot take the credit for this. In Ninety Seventy-Nine, the small, seaside town - "where most men are called Jim, John or Davey" - is portrayed uncompromisingly, the unflattering, addled backdrop to Cameron's miserable, isolated 13th year on the planet.

Mercifully, Musselburgh does not feature in her latest book, The Naked Drinking Club, in which 24-year-old Kerry swaps Scotland for drunken, drug-fuelled debauchery in Australia. Like its predecessor, the book is based on Cameron's own chaotic experiences: selling mass-produced oil paintings door-to-door as if they're originals, drinking incontinently, having sex with whoever is handy, while desultorily trying to find out who her birth parents are. Kerry, like Cameron, is adopted. This, she says, is something else she shares with several fellow stand-ups. That and the need to be accepted and loved by surrogate parents, such as an audience.

As she dips into her pool-sized bowl of muesli, Cameron talks candidly about her past, much of which, she says, is beyond recall. She has been in fights, hospitalised, arrested. On the way home from gigs she would be routinely sick in the train's toilet. Days on end were spent on benders. Rooms were trashed, friends left abused and discarded. In the late 1980s and early 1990s she was part of an "incredibly hedonistic" gay scene, "a crowd of like-minded, maladjusted, drunken lunatics. And it was just drugs, alcohol, sex, debauchery, playing pool, scam I don't believe in no regrets'. Or that it's made you what you are'. That's all f***ing shit. You just have to deal with the fact that you're a waster. I have wasted much of my youth."

Cameron was born in 1965 and she now knows who her birth parents are, having met them for the first time in Newcastle when she was 22. Towards the end of The Naked Drinking Club Kerry's newly discovered mother tells her: "I had no money and I couldn't keep you, I had no choice! You're a lovely girl, and I wanted what was best for you. I would have loved things to be different but they're not, so we just have to get on with it. I hope you find happiness, really I do, and I'm sorry."

Whether this is an echo of what happened when Cameron and her birth mother met or what the former wanted to hear is a matter of speculation. What is clear is that the parents who brought her up adopted her throughtheEpiscopalianchurchin Edinburgh, of which they were members. In 1972, the family moved to Musselburgh and shortly thereafter Cameron's mother told her "in the nicest possible way" about her adoption. The poet Jackie Kay, another adoptee, has written that when her mother told her she wasn't her real mother she was "scared to death she was gonnie melt". Cameron does not express it quite so pungently but from the moment she learned of her origins she felt stunned and shocked, confirming, she says, "an oddness about myself I had already felt".

It also proved a watershed because from that point on she changed, consumed by an overwhelming sense of loneliness and the need to be accepted. In Ninety Seventy-Nine, for instance, she recalls how she pursued boys and girls indiscriminately. "By the age of 12," she writes of her relationship with boys, "I was officially a slag, a cow, and a whore. I couldn't f***ing win. This was my lot and it was all my fault. I gave it all up to them too early, because that's what they wanted - and in my naive logic I thought if I did what they wanted they would like me for it. But instead they hated me."

There is, though, another side to the silhouette. Wild child as Cameron may have appeared, she was also, she insists, highly conventional. At a time when wearing a schooluniformwasatbestseenas eccentric and at worst made you a target for bullies, Cameron attended Musselburgh Grammar dressed like one of Jean Brodie's crème de la crème. Her shoes shone like wet cobblestones and a spotless hankie poked from her top pocket. In class, her hand shot up like a rocket and she attended the Girl Guides religiously. She routinely won prizes for her poetry and short stories. Most mornings she went to swimming training and at weekends she played hockey.

In her sixth year she was appointed head girl and the world ought to have been her oyster. On the downside, however, was the fact that she was academically wayward. Though she excelled in English and art, she was a poor speller and her concentration was bad. Maths proved beyond her and she was dumped in a remedial class where the teacher left the room for an hour allowing anarchy to reign and the "lunatics and murderers" to smash up the desks and chairs.

Come sixth year, however, the neds had been jettisoned, and Cameron began to enjoy school. Art was the subject which most engaged her. She had already attended life classes at the Edinburgh College of Art and painted herself, her boyfriend and her girlfriend naked. Egon Schiele, the Austrian Expressionist renowned for his nude studies, was her greatest influence. Her precocity, however, would count for nothing if she could not acquire the required number of Highers and she knew instinctively that this was beyond her. When notice of her conditional acceptance arrived, she says, she didn't get excited because she didn't want to build up her mother's hopes. Her father, who died from cancer in the fateful year of 1979, had left her a little money in his will.

"My mum said that dad had left that for me for art college to buy materials or something. It really broke my heart. So that when I got this acceptance, instead of going, OK, I've got three months to really study,' I went, that's a shame' - because I knew I wouldn't get the results."

When she told her art teacher about the conditional place, he tapped her playfully on the arm with his newspaper. It was, she says, near tears, "a brilliant moment". Then he walked away, she recalls, because he didn't want her to see him emotional. "I watched him walk down the corridor and I thought, I'm going to let everyone down.'"

And so it proved. Come the exams she breezed through art and English. Everything else, though, was as she'd predicted. She ended up writing statements on the papers explaining why she shouldn't have to do them. On some, she wrote poems. Then she left. "I threw away my future," she says bitterly. There was nothing her mother could say. Back then, says Cameron, they weren't close, as they are now. Her mother was in her 40s, a widow who had lost her job, suffering terribly from psoriasis. "And you have to remember," she adds, "it's a different era. It's pre-bloody-Oprah Winfrey."

She saw her art teacher, Ian Patterson, a year later, after she had left school and started to drift. In Nineteen Seventy-Nine, she acknowledges that she let him down badly. "He never spoke to me much after that," she says. "He was very hurt that I'd wasted my talent. He said, Do you know how many times in a teacher's career a pupil comes along with your talent? Maybe once, and you're mine.' I saw him in the Botanical Gardens in Edinburgh and I went up to him and he said, You know what kind of an artist you are Rhona? You're a piss artist.' And he walked away. He died of a brain haemorrhage the next year. I was 19 and I was living away from home. I found out from my mum. I was distraught."

The memory remains raw. As does the thought of what might have been. Did it never occur to anyone that Cameron may have been suffering from dyslexia, which would explain her ropey spelling, uselessness with numbers and lack of attention span? The thought has never occurred to her, let alone anyone else. But it occurs to me that cataclysmic as 1979 may have been, it was 1983 that sent Rhona Cameron for so long off the rails. It could explain an awful lot.

Rhona Cameron is appearing at the University of Aberdeen's Word Festival on May 12 at 5.15pm. The Naked Drinking Club is published by Ebury Press at £12.99