In my experience you wont necessarily save a great deal of money when you factor in accomodation, living costs, travel, insurance (you will need to get some), licence and medical conversions, and then, the EASA bods probably wont let you log any time as P1 if it was with an isntructor in USA. From my experience, I tried that route, and in the end came back and did it cheaper in the UK. It may have changed but I wouldnt advise doing a great deal of flying over there. Sure, go do some. The IR is another issue. Yes you can do it in an R22, but you can also get the same sort of procedural training in a standalone box at places like Helicopter Services in Wycombe I think.
Thing is, you still need the Multi engine rating before doing the IR course. It's still not going to be cheap, and the ATPL itself is a long way off. Make sure you hit all the requirements in the time allowed. I fell foul of the 36 month rule (not sure if its changed now) and had to do all IR exams
Most of all, try to just get as much out of the flying as possible. Visit places. Dont just bash the circuit. Do cross countries. Visit companies. Be pro-active for the future, wherever you fly. And good luck.
all of the above may have changed since I did my training what with EASA but I can bet its still a minefield.