Martin,
I am currently serving as a pilot in the RAF and have read the threads about your situation. Although getting a footing in the armed forces is a step in the right direction for you obtaining civilian licenses I don't believe that the Regiment is a very wise move; yes they do give you the opportunity to get airborne (and jump out!) but they really have nothing to do with flying wings within RAF structure, especially if you enter the lower echelons as a gunner. I don't know if you have spent time explaining your situation to the staff at your local AFCO. They tend to be knowledgeable but will try to push you in the direction of certain trades in which the RAF is lacking, it is worth being a little pushy yourself and trying to gain information on trade groups that do work closely with aircraft. If you were to do this then the technical knowledge that you would gain would be hugely beneficial if you do eventually pursue a career in aviation, it will put you in better stead than knowing the ins and outs of a rifle!
One huge advantage of joining up, regardless of what you choose to do, is that pretty much every flying base will have a flying club. They offer very competitive rates for tuition and, once you have your PPL, for rental. It is a great deal cheaper to learn to fly with an organisation such as this than a civilian flying club. You can check most of them out on the web. What's more they are a very cost effective way of building your hours in the longer term.
I hope this is of use but I do urge you to consider all of your options before you make a decision on which trade group to join. Good luck.
Axel