BRUSSELS (AP) — Leaders of 27 European Union nations gave British Prime Minister Theresa May an early Christmas present on Friday, declaring that Brexit talks can move on to their next phase: transition and future relations. But there is hard work and uncertainty ahead when negotiations resume in the new year.

Here's a look at what's next.

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WHEN DO THE TALKS START AGAIN?

Talks on phase two are set to begin in January. The early priority is to establish a transition period, probably of about two years, to ease Britain out of the EU. But the EU also wants to hear more from London about how it sees their future relations — a subject on which the British government itself is divided. Once that becomes clearer, more negotiating guidelines will have to be endorsed, probably at a summit in March.

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WHAT WILL HAPPEN DURING THE TRANSITION PERIOD?

After Britain officially exits the EU on March 29, 2019 it will lose its seat on the European Council, the body representing the 28 member states. It will have no more lawmakers in the European Parliament, and any judges it has on EU courts will be removed. At the same time, the EU is demanding that Britain respect all EU laws, and that Europe's top court, the European Court of Justice, should remain the arbiter of any disputes. In essence, it means that Britain will have to obey the rules without having any say until 2021.

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WHAT KIND OF TRADE RELATIONSHIP WITH THE EU DOES BRITAIN WANT?

That's unclear. The British government says it doesn't want to adopt any existing model for trade: not the Norway model, which involves adhering closely to EU regulations in return for access to the single market; and not a more limited Canada-style free trade deal with the bloc. Brexit Secretary David Davis has suggested a "Canada plus plus plus" deal.

The British government itself is divided on how much economic autonomy it is willing to give up to secure close economic relations with the EU.

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CAN BRITAIN FINALIZE A NEW TRADE DEAL WITH THE EU BEFORE BREXIT?

The short answer is no. It can negotiate with its EU partners, and establish the terms of its future trade relations, but no agreement can be concluded until it is completely out. By the same token, Britain cannot formalize trade agreements with other countries until it has left altogether. The EU is also wary of granting the U.K. any special trade concessions, because it has clauses in trade pacts with other countries that would force the bloc to update those deals to match.

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WILL THE SECOND PHASE BE HARDER THAN THE FIRST?

That's unclear. European Council President Donald Tusk has suggested this will be the case. It seems the most complex issue remains the border between EU member state Ireland and Northern Ireland, which is part of the U.K. A separate stream of negotiations on this issue alone will continue throughout the second phase. At the moment, no one appears to know how Britain can leave the European single market and customs union, yet maintain free movement and trade across that border.

And time is tight. Everything has to be wrapped up next fall to leave time for parliaments to ratify any final Brexit deal before March 2019.