UK ATOs were able to set up EASA equivalents before exit day subject to the main place of business rules or, alternatively, apply for fast track direct EASA approval starting the day after exit day. Most have taken the latter path and can offer both UK CAA and EASA ticks for the same course. My recollection is that the exchange rate was £1 = €1.11 around exit day and is now at €1.18, so the other way round I think, its the euro what has gone down relative to the pound.