TheInquisitor, when was your last day of service? Your QSP credits can be claimed for up to one year from your last day of service.
To secure credit from the modular CPL course, in addition to being an ex-QSP, you need to show evidence of having flown not less than 70 hours as pilot-in-command of military aeroplanes or civilian registered aeroplanes other than microlights. As a minimum, therefore, it seems that you need to gain 12 hours PIC sharpish! You can probably do that at a RAFFCA flying club; there is no actual need to obtain a PPL though.
If you left more than 12 months ago, then it seems that you'll need to meet the normal CPL criteria, although your previous flight time will be allowable towards the specific criteria, but it would seem that you would then need to hold a PPL(A).
You are one of the many RAF ME pilots who have found themselves disadvantaged by the woeful lack of PIC time resulting from the current RAF ME training system. Years ago it wasn't unusual to gain around 140 hrs TT at a UAS including 50 PIC, then the Jet Provost course probably gave you another 125 hours TT, including perhaps 35 as PIC. AFTS then followed. But that was all dumbed down when ‘BJFT’ became restricted to prospective FJ pilots with only ‘MELIN’ training being given to prospective ME pilots between their EFT and ME courses.
Your TT should at least fast track you from 'fATPL' to ATPL as you will already have 500 hrs multi-pilot time.
Don't forget that all military accreditation wll change in April 2012, so time is of the essence. It may be simpler for you to accept that, having unfortunately not sorted yourself out whilst still serving, all you can really do at this stage is to gain a PPL(A) and build your PIC experience to 100hrs, then see what emerges? Sorry that this isn’t much help.