I started off in the RAF for 12 years and the training was first class. With an eye on the bigger picture, I managed to avoid fighters and spent most of my time as a liney on the bigger aircraft, in particular the VC10 which came in handy when I came out into the civilian world. I did my A&C Licences as part of my resettlement program and came out with 2 job offers from major UK airlines. Since then I have progressed from technician, to Certifying Engineer and a couple of stints as supervisor and management. Now back as a B1 in an outstation as I missed being out on the aircraft rather than sat in an office arguing the toss in emails. So there is a career path there if with a bit of luck you can get the right postings in the military, and I'm sure there are guys out there who worked on Tornadoes and such like and now working in the civilian airline world quite successfully.
From what I hear, due to the lack of training spaces, competition for apprenticeship with the airlines places can be quite tough, but don't let it deter you. Start talking to RAF/RN Careers as well as applying for any civilian apprenticeships you can find, then see what offers you actually get back. Either way you stand a good chance of getting to your end goal, just the military route may take longer to B1/2, but with a bit more adventure.