EU OPS 4 will be "introduced into UK" as and when EARSA bring it out - it won't have to go through the parliamentary process like JAR OPS does at the moment. You won't need OPS 4 anyway, because aerial work is already excluded in JAR OPS 3 and my understanding is that, at least initially, there will be no major changes.
The peculiarity is with the UK ANO, which does not recognise "persons essential to an operation", but merely pilots or passengers and when you are carrying passengers the flight is therefore CAT. However, once the ANO becomes essentially redundant, meaning that it will still be on the British books but unenforceable, that may well change. But then, there has always been some argument as to whether it was laid before parliament properly in the first place........
Phil