If you have some spare time I would not bother with the IMC rating but go over to the US for a holiday and do the FAA IR, you will get an IMC issued for FREE (yes free apart from £64 CAA fee), anyway on successful completion so dont really see the point of paying for something twice!
The course will cost you between $3500-4000 for what I have seen ( or £2190-2500 in real money
). Also you WONT be charged any landing or approach fees which can soon tot up on an instrument co the UK if they are not included. I have seen prices for the IMC in the UK between £2000-3000 without extras!!!!
Obviously at the end of the day this wont suit everyone as some people cant get the time off, I would advise at least 3 wks if you want to do the IR, 4 would be more comfortable though. Its a lot of flying and a lot to take in. And my standrad piece of advice - get the writtens done before you even think of leaving the UK!
Julian.