Just to echo a few of the points made by Birdlady.
To convert an ICAO IR to a JAA one, you will need a minimum of 15 hours instruction of which 5 hours can be in a FNPT1 or 10 hours in a FNPTII simulator. Included in this time should be a 170A, which is a dummy test where the school assess whether you are ready for test.
Don't forget to include in your budget to do a multi engine class rating. You will also need to have passed this before you can sit the IR
As said before, the CPL is hours as required, another 170A and to have passed the flight test. Personally, if you are current and proficient on instruments, I would convert the IR first then sit the CPL.
Oh, and don't forget the test fees for the CPL and IR in your budget as well. Currently weighing in at a whopping £637 each.