Farnborough College I can certainly recommend - especially as you live in the area.
I guess the major employer locally would be QinetiQ.
Regarding the salary and hours etc I feel it is far too early to think about those as you are some four years from being a graduate.
Clearly you must talk to the college. Such a course will need a lot of effort on your part as the subject is not a soft option at all. If the college can suggest a route to enable you to study with them then the rest is down to you and how determined you are. In my view even a hard first degree is achievable by many people provided they really can taste how much they want it.
As to your age then it should help with the course as you will have grown out of many of the distractions that younger students face.
I would also suggest that after you graduate your achievement in doing that at your age will really impress any potential employer.