Unfortunately, you do now have to be an ATC cadet to be awarded a RAF Flying Scholarship.
I was awarded an RAF Flying Scholarship back in 1999, and I was not an ATC cadet. However, the rules have now changed. If I'm correct they only offer 10 hour scholarships now.
The Guild of Air Pilots and Air Navigators (
www.gapan.org) offer full PPL sponsorship. I was awarded full PPL sponsorship from the Guild, and I can highly recommend them. They should be advertising shortly for the 2005 applicants.
The Air League also offer partial sponsorship.
Good luck.