Sponsorship doesn't exist anymore. I doubt it will ever exist, why would an airline pay for pilots to get trained when the pilots are more than willing to pay for it themselves?
The RAF bases usually have RAF Flying clubs, you can usually get flyign at these clubs for about £80 an hour compared to £150 or so an hour at other clubs. After you've got your PPL you could join a local flight school and do your commercial training and work your way up.
Might take you a couple of years, after that you'll be ready to become an instructor or try and become an airline pilot.
You should be trying to become an airline pilot debt free (or with as little amount of debt as possible) so working and flying is an excellent idea. You never know, you might end up becoming an instructor at the RAF flying club before joining the airline.
My suggestion, if you havent already go to your local flying school and get a trial flight. Many people think they want to become pilots but when they actually start flying they end up hating it.