British MPs this week finally have to decide how and when they want to leave the European Union, with just days to go before Britain's scheduled departure on March 29.

They will vote again on Prime Minister Theresa May's withdrawal deal and, if they reject that, will vote to either leave the bloc with no agreement or delay Brexit.

Here are the key dates in what could be a momentous week:

MONDAY, MARCH 11 

May could go to Brussels to finalise any changes she has secured to the Brexit deal relating to the so-called Irish backstop.

The EU has refused to reopen the text but is offering further guarantees about the operation of the backstop, an arrangement to keep open Britain's border with Ireland.

The deadline is Monday night when May must put down a motion in the House of Commons to allow MPs to vote on the deal on Tuesday.

TUESDAY, MARCH 12

The House of Commons votes again on May's deal, just over two months after rejecting it on January 15 by 432 votes to 202.

May will open the debate, from around 1245 GMT, and votes are expected from 1900 GMT.

WEDNESDAY, MARCH 13 

If the deal is rejected, MPs will vote on whether Britain should leave the European Union on March 29 without any deal at all.

THURSDAY, MARCH 14

If MPs reject a "no deal" exit, they will vote on whether to seek from the European Union a "short, limited" delay to Brexit.

May has mentioned the possibility of a three-month extension, ending before the new European Parliament meets for the first time in early July.

THURSDAY, MARCH 21/22

EU leaders, including May, gather for their final summit in Brussels before Britain's scheduled departure.

FRIDAY, MARCH 29

Britain leaves the European Union, unless the process is formally delayed -- or revoked, an option nobody is discussing.