I can't speak for the civilian operators in the UK/Euro, but here in Australia, some large operators (like Qantas) will happily take on "mature age" apprentices, that is, those over 21 years old when they begin their apprenticeship. I was one such apprentice and was paid roughly 90% of full wage for the duration of my apprenticeship. Another upshot to the civilian world (besides not getting deployed) is your employer may pay for you to acquire your B1/2 license, saving you the cost of self-study and self-funding your exams.
I agree with the other sentiments expressed here: as a uni grad, you're in with a good shot as an officer IF you want to be in the forces. If aircraft maintenance is what you really want to do, ask around to some civi operators and you may be surprised.
As I said, I'm in Australia and so can't speak for operators in the UK, but the days of apprentices being only 16, 17 or 18 are either going or gone.
Of course if you're happy enough to move overseas, Qantas is recruiting right now!
Best of luck and keep us informed!