Don't do the writtens at a UK flying club. I doubt many would know how to teach for the FAA exams anyway.
Do the study at home, with the Gleim books - they are excellent. Just learn it all, and you'll pass nae bother. But learn it WELL, because the oral bit of the checkride is harder than the writtens and the same subjects come up. In fact, the bits you get wrong in the written are listed on the certificate, and the examiner will concentrate on those to see you've learned it properly now.
There is a chap at Norwich who can do the writtens for you, using the Lasergrade system.
Then, for the checkride, use the ASA "Oral Exam Guide". That's ESSENTIAL. If you learn that book off pat, you'll pass that bit too.