It's simple, take the PC terms and conditions.
Pass IOT (Initial Orifice Training); EFT (Elelmentary Flying Training); BFJT+AFT, DHFS or ME Training; and pass an OCU.
You will then have to do 6 years productive service. After which you can leave the RAF by submitting an application for PVR (Premature Voluntary Release).
Provided you have done 6 years productive service you will be able to leave. It will take about 9-10 years to get to that point, I know because I'm currently doing it!
Good luck.