The European Union has set Britain a March deadline to decide what kind of trade deal it wants after Brexit, amid concern in Brussels that the UK doesn’t know what it wants to get out of its departure.

Talks on the UK’s future relationship with the EU will not start in earnest in Brussels until spring 2018 despite Theresa May’s breakthrough last week amid concern that the UK hasn’t made up its mind.

At a summit in Brussels on Friday leaders of the 27 EU countries are expected to give the go-ahead to their negotiators to talk about “some elements of a framework for our future relations”. But they are are also expected to instruct chief negotiator Michel Barnier to focus mostly on the transition period, where Ms May was more specific in her Florence speech.

“When it comes for the framework for future relations we expect more clarity from our UK colleagues about what the end state, their end objective is,” a senior EU official said ahead of the summit.

“I would say that the time between now and the March European Council is the last call to London to put more details on what is their vision of the framework for the future relations.

“Until now we have heard it’s no single market, no customs union, but it’s a bespoke partnership. If no new elements will come from London then we will work on that basis. We will work on the basis of no customs union and no single market.”

Leaders will meet to discuss Brexit on Friday after other business at the European Council has been dealt with – including migration quotas and the creation of a European Monetary Fund.

It is understood that EU officials were spooked after Chancellor Philip Hammond told MPs earlier this week that the Cabinet had not yet discussed the end goal of Brexit, while Brexit Secretary David Davis revealed to another committee that the 58 studies into Brexit’s impact, which he previously claimed existed, did not in fact exist.

A European Commission communiqué to the European Council, released on Friday, illustrated the doubts in Brussels about the practicality of the UK’s approach, warning that it “seems hard to reconcile” the UK’s plan to leave the single market and customs union with commitments made over Northern Ireland in the first phase of talks.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

Despite the Commission’s wish to focus on the transition period because of its clearer terrain, the issue could still present stumbling blocks. One key row is likely to be on whether the UK will automatically adopt new EU laws without a say in drawing them up after 2019.