LONDON (AP) — After months of spats and false starts, Britain and the European Union ended 2017 by agreeing to have an amicable divorce. In 2018, they have to find a way to live together in the future — and that’s when things could get complicated.

In December, the EU declared that “sufficient progress” had been made on divorce terms to start negotiating future relations, including trade.

It’s a vast task that means striking deals on everything from automotive parts to intelligence-sharing. Time is tight: Britain is due to leave the bloc in March 2019.

And the two sides have differing — even contradictory — visions.

Maike Bohn of EU citizens’ lobby group The3Million predicts that 2018 will be “messy. Not everything is resolved and there are some big, crucial gaps.”