On Thursday, 21 March, EU leaders offered to delay Brexit until 22 May if MPs approve Mrs May's deal and said if they voted it down then the UK would have until 12 April to decide whether to accept a no deal Brexit.
But what is so terrible about a no deal Brexit and why are so many MPs so keen to avoid it?
Trade between the UK and the EU could be severely affected.
Understand Number 10 now seriously considering indicative votes on Brexit next week. Government source tells me there could be 7 options: PM deal, revocation, second ref, deal + customs union, deal + customs + single market, FTA or no deal— Kate McCann (@KateEMcCann) 22 March 2019
The UK government has rolled over existing EU trade agreements with Israel, Switzerland and Chile as well as aviation services with US and Canada and nuclear deals with Australia.
But it is not clear what concessions it will have to make to other countries to get them to roll over EU agreements.
The biggest difficulty for Britain though is the tariffs which would be imposed on imported and exported goods.
Earlier this month the UK government said it would scrap 80 to 90 percent import tariffs on goods, in order to keep food and commodities prices down for consumers and manufacturers.
Whatever happens in the coming days, one thing is clear: the Prime Minister has no mandate and no right to threaten our country with a no deal Brexit.— Keir Starmer (@Keir_Starmer) 21 March 2019
If she is unwilling to show leadership at a time of national crisis, then Parliament must be given the chance to do so. 3/3
Britain imports 90 percent of its lettuce, 80 percent of its tomatoes and 70 percent of its soft fruit from the EU, according to the British Retail Consortium.
Law and Justice
The Home Secretary, Sajid Javid, has written to his counterparts in the EU27 asking for them to put contingencies in place in the event of a no deal Brexit, but has had no reassurances.
British police officer carry out 539 million checks on the Schengen Information System (SIS) every year — checking on EU nationals' criminal records in their home countries.
Last month the National Police Chiefs' Council lead for Brexit, Deputy Assistant Commissioner Richard Martin, said Britain would be "less safe".
Today’s Berliner Morgenpost: “This is how expensive Brexit will be” in the case of No Deal. €115 per head GDP loss on average, and as much as €170 in Hamburg, €126 Düsseldorf, €115 in each of Cologne & Munich. pic.twitter.com/kiveWmdgq5— Greg Hands (@GregHands) 22 March 2019
"Will we be less safe? Yes. Will criminal gangs be running amok? No. But will it make our jobs more difficult, yes," Mr. Martin said.
"Crime is by its nature borderless….organised criminals are entrepreneurs of crime…and if there is a gap to exploit I'm sure they would," Mr Martin told a briefing in London.
Mr. Martin said the EU Arrest Warrant would also no longer work in the event of a no-deal Brexit.
He said the system would revert back to the 1957 Convention on Extradition which would be a "much slower and clunkier process".
Mr Martin said before the EU Arrest Warrant the UK extradited around 60 people a year — now it's almost 2,000 a year.
The government will continue to accept EU-approved medicines but the EU has said UK pharmaceutical companies will have to re-register their products in order to sell them in Europe.
So it seems the EU will give UK an extra two weeks to avoid a no deal Brexit. Imperative now that Parliament takes control away from PM and uses that time to agree a way forward — preferably asking for a longer extension to put the issue back to voters. https://t.co/joglPYaDld— Nicola Sturgeon (@NicolaSturgeon) 21 March 2019
The UK government has asked hospitals and UK companies to build "buffer stocks" of key items to deal with any interruption to supply.
The Department of Health has also bought warehouse space and secured additional freight capacity for shipping medical goods to the UK.
British adults, including lorry and coach drivers, would not be allowed to drive in EU countries without a special driving permit.
UK tourists could also end up paying more to use their mobile phones in Spain, France, Italy and Greece.
Border checks would be re-introduced at British airports and ports and on the land border with the Republic of Ireland.
This could potentially resurrect dormant Irish republican groups, like the IRA and the INLA, who have long fought for a united Ireland but laid down their arms after the Good Friday Agreement.
HM Revenue and Customs has been talking to businesses about how the customs process would work in the event of no deal but many businessmen and women are still unaware how they will be affected because the UK and EU economies are now so closely enmeshed.
The UK has offered EU citizens who are in the UK before 29 March 2019 can gain the right to remain and eventually become UK nationals.
But in the event of no deal there would be no such offer to the millions of UK nationals who live in the EU27, especially tens of thousands of people who retired to Spain or Portugal.
Diplomatic notes show Merkel interventions were limited but when she did make them, it as a truth bomb to remind Ireland about the realities of a no deal for the border #Brexit #euco pic.twitter.com/UbMAn8LJ57— Mehreen (@MehreenKhn) 22 March 2019
The rights of UK nationals would vary depending on each country.
In the event of no deal it would be up to the UK government to decide what to do with EU citizens who arrive in the country after Brexit.
The government has said it will to continue to allow EU agri-products into the UK even in the event of no deal.
But again UK exporters of goods like lamb, beef, fish, grain and vegetables would have to go through protracted bureaucracy in order to be able to export to the EU27.
When Britain leaves the EU — deal or no deal — we will be exiting the Common Agricultural Policy, which currently gives generous subsidiaries to British farmers in certain circumstances.
The UK has promised a new environmental watchdog to replace EU functions, such as air pollution but it will not be in place until 2021 so some complaints may just sit in an in-tray until then.
The Competition and Markets Authority will also be expanded as it takes on the work currently done by the European Commission when it comes to monopolies and cartels.
Places like Cornwall and west Wales, which ironically voted strongly to Leave in the 2016 referendum, actually do very well from EU grants, which will soon be drying up.
Iain Begg, a professor at the European Institute at the London School of Economics, said the grants would disappear with or without a deal.
"Although some research grants may last until 2024, the bulk of the grants from the EU will have been spent by 2022," Prof. Begg told Sputnik.