THERESA May has been compared to a “rabbit caught in the headlights” as she warned the UK will enter uncharted territory if her Brexit deal is voted down.

The Prime Minister insisted she will set out further assurances over the coming days as she prepares for a dramatic fortnight in Westminster which could define Britain for decades to come.

She insisted a meaningful vote on her Brexit divorce deal will go ahead on or around January 15, but raised little hope further concessions will be thrashed out over the controversial Irish border backstop.

Mrs May said she had been talking to European leaders since postponing the vote last month and had secured “some assurances”.

Speaking to the BBC’s Andrew Marr Show, she said: “What we’ll be setting out over the next few days is assurances, measures in three areas.

“The first are measures that will be specific for Northern Ireland. The second is a greater role for parliament as we take these negotiations into the next stage for our future relationship.

“And the third, and we’re still working on this, is further assurances from the European Union to address the issues that have been raised.”

The Brexit process is currently in deadlock over plans to avoid a hard border on the island of Ireland if the UK leaves the EU without a deal.

In December, Mrs May was forced to postpone a vote on her withdrawal agreement after it became clear she would suffer certain defeat.

Speaking to the BBC, she repeatedly failed to rule out holding a vote in Westminster multiple times as she seeks to push her deal through.

But she added: “If the deal is not voted on at this vote that’s coming up, then actually we’re going to be in uncharted territory.

“I don’t think anybody can say exactly what will happen in terms of the reaction we’ll see in parliament.”

She also reiterated her strong opposition to a second Brexit referendum, insisting: “It would divide our country. And practically, actually you couldn’t get a referendum in time before March 29.

“You would be talking about extending Article 50. We’re already nearly three years from the vote to leave the European Union.

“I think we should be leaving the European Union and delivering on that vote.”

She said no alternative plan was able to respect the 2016 referendum result, protect jobs and provide certainty to citizens and businesses, and also warned of the "danger" of ending up with no Brexit at all.

But SNP Westminster leader Ian Blackford insisted her deal is “dead in the water” and compared Mrs May to “a rabbit caught in the headlights”.

He said: “Theresa May has had two weeks to reflect on her handing of Brexit, but this interview showed that she has not moved an inch or listened to any of the concerns being expressed right across the political spectrum. Groundhog day isn’t supposed to be for another few weeks.”

He also accused the Prime Minister of an “uninspired attempt to re-brand a no-deal scenario” after she referred to it as a "clean break Brexit".

It comes as officials prepared to test the repercussions of a no-deal Brexit by paying up to 150 hauliers to queue up near Dover during rush hour today.

Meanwhile, Tory and Labour MPs will launch a parliamentary campaign to rewrite Government legislation to block a no-deal Brexit.

Nigel Dodds, deputy leader of the Democratic Unionist Party, insisted the fundamental problems with Mrs May's "toxic" deal remain the same.

He said: "This is a time for the United Kingdom to make clear what it wants and needs for a Withdrawal Agreement to pass parliament so that the EU is in no doubt as to what's required for a deal.

"The backstop remains the poison which makes any vote for the Withdrawal Agreement so toxic.

"The EU has shown in the past that it will move but only if faced with a resolute red line on the part of the UK Government.

"The coming days will show if this Government is made of the right stuff."

Elsewhere, Mrs May accused Labour of "playing politics" and opposing any deal to create "the greatest chaos" possible.

She will attempt to win over Tory MPs this week during drinks receptions at Number 10.

Officially slated for the week of January 14, the Commons vote is widely expected to be held on January 15.

UK Health Secretary Matt Hancock said he was "confident" that medicine supplies would be "unhindered" in a no-deal scenario – as long as the pharmaceutical industry took action.

Asked if he could guarantee that no one would die as a result of a no-deal Brexit, Mr Hancock told Sky News' Sophy Ridge On Sunday: "I'm confident that we will have the unhindered supply of medicines so long as the plans that we have in place are properly enacted."