I was in the same position as you a couple of years ago. My long term AME had retired, been looking after me for 35 years. I had been flying more recently on N reg a/c (FAA).. Needing to find another AME I tried Gloster Aviation Medicals at Gloucester/Staverton. He picked up on a small issue with my right eye.. something I'd been flying with for my entire career.. No only did he refuse my medical, he faxed off his results to the FAA HQ at Oklahoma.. I was then told I would have to attend the FAA medic center at OK.. maybe take a flight test etc etc.. a few thousand $$$$$. Unless you're in perfect shape I'd give Gloster Aviation medic. a very wide berth.