Talk to some people who have done the FAA IR then immediate conversion to JAA. Those I have met have said that it wasn't worth doing the FAA first, the training was of little use towards achieving the JAA rating. Take that false saving out of your figures and you come up with pretty much the same costs as you could find the training for never leaving the UK, if you are creative with your hour building (say using the money you have ready for the CPL/IR to buy a share, then sell the share when you have the hours at a very good rate for little or no loss).