Get cracking NOW!
WannaBeCiv,
Bristol Groundschool: I believe, as I have said many times before, that this place is unbeatable for military guys wanting to pass the ATPL exams. Alex Whittingham and team are masters at teaching you how to pass the exams. Sure, you will learn useful stuff on the way to that goal, but you won't dwell unnecessessarily on trivia getting to that point (although the exams do contain a lot of trivia you will never see or hear of again).
I can't help feeling that having ALL the requirements met before applying for jobs makes it much easier for those prospective employers to gauge what/who you are. Without the ATPL in your sticky mitts, you may be viewed as no better than an enthusiastic aviation buff who might get job as a pilot ...... some day. IMHO.
If you are only 2 years from ejecting from the RAF then you have left yourself some work to do. Prepare yourself mentally for some hard work. You need to arrange all the 'bits' that people have mentioned here as well as apply for potential jobs and ramp-up for the whole leaving the RAF thing. You are going to experience stress, I think. I had my license sorted and issued 3 years before my exit date but the last year alone, with job apps, resettlement, renew IRT and Class 1 Med, leaving RAF etc etc was quite a rollercoaster. Get cracking with it NOW! Just because your CV gets out there does not mean prospective employers will come back to you by next return of post. I had 2 offers for interviews from major far east companies nearly a year after making the applications ....... and I had already been in employment with a UK major for several months!