Now it's just a case of finding a way of using the CFI certificates in the UK! (Suggestions welcomed!)
As long as it is a N registered aircraft you can give all CFI services, e.g. (basic) flight training, Flight Reviews etc. You could as well give a Flight Review, IPC in a none N-reg. aircraft, provided that the PIC holds the appropriate license (JAA/EASA) according to the aircraft registration and of course is current, in terms of JAA/EASA requirements.