UK Members of Parliament will voted on Wednesday night at 7pm local time GMT (6am Thursday Australia time) on whether the UK should crash out of the EU without a deal.
The EU is most likely to agree to a short extension for Britian to leave the EU after March 29, possibly through to May before elections to the European parliament are held.
Other options could be a second referendum or a snap election. There is also speculation cabinet Ministers could call on Prime Minister Theresa May to quit.
Mrs May has angered pro-Brexit members of her party by backing the delay with some telling The Sun a split in the party could not be avoided.
"The party is going to be fundamentally divided over this. We're totally f****d," one said.
A group of Conservative MPs from across the Brexit divide, including have tabled an amendment to tonight's vote on the so-called "Malthouse compromise".
Their motion called for a post-Brexit transition period of up to three years even in a No Deal scenario, which would give both sides the time to establish a future trade deal.
Mrs May initially planned to order MPs to vote against the amendment, but reportedly changed her mind after a tense Cabinet meeting where pro-Brexit ministers said she must leave it up to individuals.
But in a sign of the danger the UK now finds itself in, even that is far from certain to actually happen.
Even if the Malthouse plan were approved by the House Commons, the EU would be unlikely to agree a transition period without a comprehensive withdrawal agreement in place.
A defiant Mrs May who is battling a bad sore throat and has almost lost her voice, told parliament: "I may not have my own voice, but I do understand the voice of the country."
She was scathing of the Labour leader Jeremy Corbyn.
"He doesn't agree with Government policy, he doesn't even agree with Labour Party policy - he has nothing to offer this country."
The new votes come after Mrs May's Brexit plan suffered a second humiliating defeat 391-242 - a margin of 149 votes, the fourth worst in British political history.
That defeat is what has led to such unpredictable times.
"I continue to believe that by far the best outcome is that the UK leaves the EU in an orderly fashion with a deal, and that the deal we have negotiated is the best and indeed the only deal available," she said last night.
"If the House votes for an extension, the Government will seek to agree to that extension with the EU and bring forward the necessary legislation to change the exit date commensurate with that extension."
She said there are now three tough questions for the Commons to answer.
"Does it wish to revoke Article 50? Does it want to hold a second referendum? Or does it want to leave with a deal, but not this deal?" she asked.
"These are unenviable choices, but thanks to the decision the House has made this evening they must now be faced."
A spokesman for European Council President Donald Tusk, representing EU governments, said Britain would have to provide a "credible justification" for any request for a delay.
"We won't know how long that extension will be, that's for them to decide. We won't know what conditions will be attached," Brexit minister Stephen Barclay told BBC radio.
Supporters of Brexit argue that, while a no-deal divorce might bring some short-term instability, in the longer term it would allow the UK to thrive and forge trade deals across the world.
The UK government today outlined its plans to eliminate import tariffs on a wide range of goods in a no-deal Brexit.
Unveiling details of a tariff plan that would last for up to 12 months in the wake of a no-deal Brexit, the government said 87 per cent of total imports to the UK by value would be eligible for tariff-free access, up from 80 per cent now.
It also promised not to introduce new checks or controls on goods moving from the Irish Republic to Northern Ireland - a major concern among Irish politicians who feared a hard border could see a return of violence in the province for more than 30 years until the 1998 Good Friday peace accord.
The EU said there would be no more negotiations with London on the Withdrawal Agreement, struck with Mrs May after Two-and-a-half years of negotiations.
