Martin,
Good initiative to display the interest. If you want to be involved in RAF aircraft engineering there are 2 ways in: 1. join as an Aircraft Maintenance Mechanic, having been pre-selected into either (M) mechanical trade or (Av) Avionic and electrical. or 2. Weapons technician.
under (1) you join, do basic at Halton then go to Cosford for AMM training - about 18 weeks or so. Then out onto a squadron to carry out flight servicings and minor, supervised rectifications for a period between 18 months and 4 years on low pay, being the brunt of much extraction of urine and being accused of being a 'Flem'. Then, subject to performance, back to cosford for another 12 months to be trade trained, then back out to a squadron as a tradesman.
under (2) you join, do basic at Halton then go to Cosford for Weapons trade training for about 12 months, then out to a unit on the low pay band until you achieve Q-OPS which brings a huge pay rise and the oportunity to progress further.
Best bet is to get all the info from the Careers office, get any promises put in writing!
Good luck.