Jking, RE: medicals,
ATCO's now have to have the new European Class 3 medical. I believe its almost identical to the the the old class 1 and ATCOs who previous held a class 1 were able to switch to the euro class 3 by renewal... not sure what the situation would be for you though seeing as yours has expired. Probably best to give NATS occupational health a ring as they'll be able to answer.
I might be wrong but I think NATS reimburse travel expenses if you do have to go to Gatwick (again, best to check with OH).