All I would add to that is make sure that you are proficient at flying a small light twin and that your NDB tracking / holding skills are sharp. I actually found it quite tough to revert back to a low powered light aircraft with a lot of manual / clockwork instrumentation, and my NDB skills sucked!
Be wary of the trap regarding doing your ATPL exams / CPL training in the UK and then your IR elsewhere (in JAA land) There are a few (not all) large operators that get quite agitated if you have not done all your conversion training in UK airspace, this counting particularly for the IR. All the more important if you have 1000's of hours time, but none within the UK FIR's.