Why oh why don't you just go to Stapleford (or similar) around the corner and do a JAA PPL then CPL IR Modular course and do your ATPL distance learning with someone like Bristol Groundschool?
No visas, no transatlantic travel, no conversions, no accomodation costs, continuity of training, continuity of course mates, flexibility of training schedule, networking opportunities - the list is long. Total cost need not exceed £46k ish.
Just how much do you expect to save by going to the US? If its a burning ambition then go there for 3 weeks to do your post PPL hours building or something.
The UK CAA Instrument Rating Test is by far your biggest hurdle. Be sure that all your training is assisting you wherever possible in passing it. The easiest way to achieve this is to fly at one school with one set of instructors on one fleet of aircraft in one local flying area with everyone knowing you are going all the way with your training from day one.
I've taught people to pass UK CAA PPL, CPL and IR flightests...
Cheers
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