Hi wiveny
As an ex RAF guy, there is no reason why you cannot self study the modules. Many of your old colleagues have done so before you. You will need to make some time in your busy home life and get some support and understanding from your family, but with your background you should clear all the modules in 2-years.
There is lots of support for self studiers now, with the likes of websites like club66pro.co.uk and airtechbooks.com, give them a trial and see how you get on with your first module (with your piloting experience you should find module 8 - aerodynamics, for example, a doddle).
Only problem is, if you are not in aircraft maintenance right now, you may have a problem proving your experience. It's a chicken and egg situation. You will get some dispensation if you can prove your RAF experience, on application to the CAA.
Good luck