If you can fly in the US, you can fly in the UK ! Laws of Physics don't change from the US to Europe....Besides, if you learn to fly in the US then you'll be used to their way of doing things, and it'll make it a hell of a lot less stressful if you ever go back for a flying holiday.....
Don't be put off by UK Instructors trying to protect their jobs by offering 'helpful' advice like 'you will need x hrs to convert....blah blah...'. When I first joined a club in the UK, as we were taxying out to the runway for my dual check, the instructor asked me where I learned to fly. When I said the US, his response was 'oh...we don't like those here....'...(tosser sprang to mind).... When we landed his response was 'you flew very well...'
RT...not a problem. Learned at Long Beach, and did my dual check in a 'busy' class D airport....oooh...it was so scary, think there must have been at least 10 other people on the radio during my checkout and I think a 737 even came in to land!
cheers