Alan
You are correct in thinking that you can enter the US on the 90 days visa waiver, however this is not for the purpose of flight training merely holiday.
On a PPL course you are required to be on a minimum of a M1 visa as you will be completing more than 18 hours per week (minimum to be considered on a training course). Any accredited school can offer this and it is merely a matter of paperwork.
I suggest that you do go on this visa as only last week a friend was not even allowed to board at Gatwick as he did not have an M1 Visa for training.
You may look at the following web page for all the workings of the visa requirement and actions required.
http://www.usembassy.org.uk/cons_web...iv/student.htm
Good luck with your flight training!
