Having completed over 20 years as an aircraft engineer in the navy I can assure you that it is a good & well paid career. It undoubtedly helps with the ATPL theory exams and I would say give it a go, even if only for 6 years. Those people saying that you will waste your time are wrong and I agree with everything said by Icanseeclearly and A &C. There are learning credits available to service personnel that can also be used for part funding of your flying/groundschool in some cases. Whilst it isn't always great with time away from family there is always chance to do things that come free in the military but would cost £££'s in civvy street. If you can take the very rough with the smooth it is rewarding. Wether it helps with getting an airline job I can't say, ask me again in about 18 months! But it will look good on any CV and will set you aside from other similarly qualified applicants. All the best with your decision.