At the moment the position is that your UK licence will after Brexit only be valid for flying UK registered aircraft. The EU will have to recognise it as an ICAO licence for flight in EU airspace in UK registered aircraft.
The EU has prohibited EASA from talking to the UK CAA about Brexit issues and how to make any transition smooth, you have to wonder if these people have ever been our friends within the EU or just a bunch of empire builders who are having a hissy fit because they know the game it up.