AfricanSkies,
check out:
http://www.srg.caa.co.uk/pld/fcl/fcl_faq.asp
This will tell you what you have to do to convert your licence. There is no need to go through the whole thing again, as Homer has told you. Spending money on an integrated course would be mental. It shouldn't cost you any more than £12,000 to convert.
The conversion process depends on hown many and what type of hours you have, and also on the discretion of the flying school you go to. You don't have to redo the CPL, just the test, and you may not have to redo the entire IR of you find a sympathetic establishment. So the best thing to do is talk to a few schools and find out just what they are going to put you through.
As far as I know PanAm Academy and West Michigan University do JAR training in the US. Check out the CAA website for a full list of approved schools.
TB