Hi G-CEXO,
I suspect these UK flying schools are conning you for purely business reasons. Remember, a lot of them resent students going abroad instead of swelling their coffers.
And don't let anybody tell you you need a JAA PPL to commence ATPL training. At PPL level it doesn't matter which country's PPL you have as long as it is a licence from an ICAO country.
Even if you learn in the UK, you will still require a good deal of extra training to get to CPL standard. The US PPL standard is not a lower standard, quite the reverse.
Hoping to do the PPL by next March in the UK is chancey for all the reasons already given, unless you go full time to a flying school like Atlantic Fligh Training in Coventry that caters specifically for those proceeding to professional licences. And that would be expensive.
To be certain, I would definitely go to the USA.
Well that's my two penny worth.
Broomstick.