Not done it but may be the following will help.
You will need to get a CPL.
Medical class 2 (can be done here in the UK) and the writtens need to be done.
The writtens are not difficult.
There are some quirky things in the flight experience department (Check FAR/AIM = online) which you have to have done and get signed off by an FAA instructor to state that you are ready for the test.
The test can also be done her in the UK.
If you need further information about writtens and test you can do worse than ringing AFT @ Norwich and talk to Tom Hughston on 01603 301902.
HTH
FD