dontpressthat
I trained in the West Coast of the USA with an Airport with Ground/Tower/Dispatch and can confirm that UK ATC / RT is wildly different to the more relaxed (Nxxy with Information whatever, at Lake Whatever, Inbound).
Although I came back with the coverted RT license it took me a couple of hours with a FI (who had also flown in the States and assumed I knew nothing) to get the hang of it. It's no big deal - the ATC are really helpful and friendly, and if you cock up don't panic - just concentrate on flying the plane and ask for an explanation. Everyone I spoke to happily gave me more detail, with the caviat that I don't need to be told twice!
Safe Flying, and I'm pleased to know that I'm not the only one who suffered upon my return to UK South Eastern airspace!