If you want the forces lifestyle, then how can you say it's your life long ambition to be an airline pilot? The lifestyles are not even close. Two very different ball games!
As for not being able to afford an ATPL(f) at the age of 17. Errr, not many others do either! Work and save for 5 years. I know the ripe old age of 22 seems old to you, but it aint. Probably still a bit young if you ask me.
What's the market doing in 23 years? As has been said before, we don't know whats going to happen next month. However, if you want me to stick my neck out, I'd say that a low hour 40 y/o has got an up hill struggle to get a first job.
Sorry if I seem a little unfair, but I just don't understand why someone who dreams of being an airline pilot signs up to the RAF for over 20 years in a non-flying role.
I tried the RAF route. They told me my eyesight wasn't good enough. Then tried to flog me some ground position. I didn't hear what it was because I was already out of the door. I suspect you stayed behind to listen to the hard sell that they usually give to those not even old enough to drink or vote. Little short of press ganging if you ask me.
If you want to be an airline pilot, save and train accordingly. If you wan't to be in the RAF, go ahead and join (sounds like you already have).
If you want to know anymore on training for an ATPL, feel free to ask me. Feel free to PM me. I'll gladly help you.
I think you need to actually decide what you want to do first.
Good luck
EK