After a series of deadline extensions and fudged decisions, Britain and the EU are finally approaching what is very much the endgame for Brexit. In the coming weeks, the basic form of departure that will take place will most likely be decided upon. What can we expect?

What is the timetable?

Officially, one date looms large: next Wednesday, when a summit of EU leaders in Brussels will attempt to thrash out Brexit terms that are acceptable both to Theresa May and the EU27. While there have been positive noises recently, it is likely that too much remains to be done for it all to be agreed by then.

The focus would then switch to an emergency summit, pencilled in for 13 November, giving more time for movement on both sides. There is speculation that yet another gathering might then be timetabled if it is needed.

The intervening weeks will be filled with official and semi-official talks, soundings-out, ideas being floated and endless internal negotiations. Any agreement will then have to be approved swiftly by both houses of parliament – which is by no means a given – and endorsed by all EU member states before the departure date on 29 March.

What is yet to be agreed?

The two primary points of contention are connected: the Irish border and the framework for future trade and customs arrangements. Most knotty is Ireland, where May cannot have either a hard border nor a situation where Northern Ireland is aligned more closely with the EU than the rest of the UK, creating a customs border in the Irish Sea.

Adding to the muddle is the official UK insistence that the EU’s so-called backstop arrangement for the border, which would create alignment in the absence of a deal, be time-limited – something Brussels says cannot be done.

Could Tory Brexiters sabotage May’s plans?

They certainly hope they can. The European Research Group (ERG) of hardline pro-Brexit Conservative MPs is officially supportive of May as prime minister but says she must drop her proposals in favour of a free-trade-based deal that would keep the UK less aligned to EU regulations, the so-called “Canada plus” or “super Canada” option.

They and their allies are maintaining a stream of negative comments and stories about May’s Chequers plan. The former Brexit secretary David Davis wrote to all Conservative MPs on Tuesday claiming that the Chequers plan would cost the party future votes.

It remains to be seen whether this can be translated into enough Commons votes to sink Chequers: earlier ERG predictions that 80 opposing votes could be mustered have now been downgraded to about 40.

Other predictions put the number at closer to between 10 and 20. Either way, May will face a considerable amount of noise and pressure.

What about the cabinet?

A cabinet that coped with the Chequers-inspired departures of Boris Johnson and David Davis does seem more united. But even here, threats lurk for May.

Some ministers are understood to be at best tolerant of May’s plan, and would chafe at more concessions. The international development secretary, Penny Mordaunt, pointedly declined to endorse Chequers this week.

What else could affect progress?

It is still a hugely fluid situation, with any number of potential pitfalls, detours and cul-de-sacs.

May faces intense pressure from her informal coalition allies in the DUP, who are ratcheting up the pressure on her over the Northern Ireland issue. It has threatened to vote against this month’s budget if May crosses its red lines over UK customs integrity at the next EU summit.

It also remains to be seen whether the EU will be as amenable as hoped at next week’s summit. All the noises before the informal gathering in Salzburg last month had been harmonious, but it ended in humiliation for May.

So, what will happen?

Making confident political predictions is reckless at the best of times, but that goes double for Brexit.

The consensus among pundits seems to be that an agreement on some version of the Chequers deal, with compromises on both sides, is the most likely outcome. Then May could just about get the deal through the Commons, especially if some Labour MPs defy the whip to back the plan.

As the weeks pass, it seems increasingly likely that if there is a deal, it will be based around May’s blueprint. For all the ERG’s calls to “chuck Chequers”, time is running out to start from scratch with a Canada-type idea.

However, it would be foolish to rule out a range of other options, from a collapse in talks bringing a no-deal departure, to UK-based political turmoil or machinations seeing May ejected or even – though it seems unlikely – a general election.