Verbage, I have been looking into this with a view to getting out and as far as I can find out you can hold a licence in the mob but it is difficult because of the amount of experience you need on civillian aircraft to gain and maintain the licence ( I think if you are on 101 you would be fine).
You can do all modules and exams through correspondance while in the RAF from places such as
http://www.jar66.co.uk/ (expensive)
http://www.licencebypost.com/ ( not so expensive)
or Kingston university do a course too where you also gain a degree for your troubles, sorry I don`t have a link.
You can do all the exams but until you have correct amount of civillian experience you cannot apply for the licence. (Unfortunately being in the airforce accounts for virtualy nothing in the eyes of the CAA but manages to waive about 1-2 years of experience needed !).
Have a look at this link for latest standards :
http://www.caa.co.uk/default.aspx?categoryid=177&pagetype=68
Unless you can buy some used course notes it can get expensive ( just look at jar66.co.uk`s prices scary !). However looking at my course notes they are very similar to fittters course notes, in some cases easier. There are also full time courses but if you have done a fitters course you will be incredibly bored for 2 years ! and means leaving the RAF too although some colleges do give you placings in industry for work experience.
If you want a career in the aircraft industry when you leave the mob it is definately worth the bother to get your licence although it is not essential, it depends on how much you want to earn
. A lot of employers want type rated licensed engineers with a certain ammount of experience so it is almost inevitable you will have to work as a mechanic in civvy street at first although I could be wrong as everybody seems to have a different take on this.
Check out
http://www.aeroengineer.com/forum/default.asp and
http://www.airmech.co.uk/forum/ultimatebb.cgi for good gen from the guys in the industry.
This advice should not be taken as gospel as things change quickly but I think it is close enough.
Good luck
Regards Ian