Evo, thanks for your reply - its an interesting route which I'll look into further. I guess a further advantage of doing as you suggest is that you gain some US ratings as well.
When I mentioned doing the flight training in parallel with the ATPL theory I was thinking that the latter would be spread over a year or two (I have a full time job) but the flying would be likely to be done in smaller segments which I would do within the same period. In addition I would prefer to take my time with the ATPL stuff so I can absorb it properly. I had also forgotten that the theory exams had to be passed before the CPL flight test.
FujiF