Get your CAA Class 1 Medical from a service MO, it will be a lot cheaper than going to Gatwick for your initial issue. Not sure which MOs still do them, but I'm sure someone will be able to tell you. IIRC the MO at Valley would be a good bet.
As for MCC, I'd recommend Oxford. It's done on a B737-400, gives you some big jet flying and glass cockpit experience. It's a bit more pricey but will help if you go for the BA sim as that is in a B747 and the cockpits are similar. I know of people that got exemption from the MCC and subsequently failed sim checks. The MCC will give you an idea of what airline flying is about.
You'll only need to do a bridging exam and 4 ATPL exams becasue of your >2000hrs. Use Bristol GS.
Good Luck, maybe see you down route sometime....