Sometimes you do require a PPL and other companies do not require it. Your best bet for finding out about cadetships will be on these pages here, or at the back of 'Flight International' magazine, a weekly aerospace news publication that you can flick through in WH Smith. Check out GAPAN and Air League for other sponsored routes available from these trusts and bodies.
Bear in mind that there is a great deal of competition for sponsored spaces, and it is worth doing all that you possibly can to make yourself appear to be the best candidate out there - however much some may oppose it on these pages, a degree in the current climate, if you are up to it and interested in what you study, may be a wise option for you.
You say you have left school, but what level do you mean? Left sixth form of left after GCSEs? If you are not getting minimum grade GCSEs required for sponsorships, yes you can get in with money, but are you really sure that you are able to cope with an intense course and a fairly numerate career?
Good luck.