My advice would be to approach this with chunks of intensive flying with committed milestone targets. If this is a career move, I wouldn't recommend entering this process in dribs & drabs; it'll take forever and cost more.
In the first instance, I would take time off and do your PPL in America. The basic PPL is very weather dependant and could drag on forever if you hang around in the UK. The dollar conversion rate is in your favour and you could achieve that 1st milestone in a few weeks. It would probably work out much cheaper than in the UK.
From this point you could decide whether to come back to the UK and train part-time for the other parts, or remain in the US. Time is an enemy in training terms, the longer you let it run, the more you will need to fly, the more it will cost.