In the absence of any coherent plan from the UK Government for the UK's departure from the EU early next year, the CAA have produced
quite a good website with guidance including "get yourself a licence from another EASA Member State" if you want to work in Europe.
And, apparently without any consultation with the CAA, EASA has started taking, encouraging even,
applications from UK-issued EASA approval holders (organisations) for 3rd Country EASA approvals. These applications will be, of course, a good revenue source for EASA; but will it be enough to replace the EASA Membership fees that will be lost?