No need to go to the states:
Ive researched this extensively:
if you have a JAA IR you can convert this to a FAA by sitting a 2hour ground exam and having the rating tacked onto your FAA rating.
You can do either the FAA CPL either on a 114 commander or on a twin at soloflight in Humberside every three months they ship an examiner over and conduct FAA CPL & IR checkrides.
There is no neeed to go the states, however places are very limited and booked well in advance. You cannot book a checkride without completed a minimum of I beleive 5 hours with your Instructor assuming you meet all the hours requirements.
If you are a 185 hour chappy you will struggle for minimum hours if you are a relatively experienced 700-1000 hour instructorish sort of person/chappy you will probably have picked up the minimum hours requirements for FAA CPL issue.
I plan do do mine in March, I am currently studying the fantastic KING video collection so th at I can sit the ground exams at soloflight at their Laserquest exam facility. Which incidentally tells you if you have passed there and then none of this JAR two weeks for your results crap.
Its not cheap however, Mr Stewart the FAA CFI there has more hours in the flair than most of our total times put together........ and rumour has it that he charges like a wounded Rhino however he's a no nonsense guy I believe, who won't kick the arse out of a course if he thinks you are ready...... (again 2nd hand info)
It costs slightly less than doing it in the states by all accounts
Hope this helps
Soloflight's web site is here