NAV to ATPL
Don't know if this will be seen as help but, here goes.
You need to get yourself known. It won't work if you don't have a current licence. With regard to your lapsed PPL, as it has been over 10 years, I believe you will need to do the whole PPL again. With your flying 'familarity', you should be able to do this easily in the minimum 45 hours. It will still cost cicra £5,000+.
JAA approved schools in the USA are your quickest and cheapest way to regain your PPL. If you can afford the time, try and re-attain your PPL before leaving the RAF. Many of these schools realistically suggest one month. With your experience, you should be able to persuade the school to complete it in much quicker timescale. You won't have difficulty with the ground exams. Once you've got your PPL, blag as many trips as possible in anything and everything, and that includes sims. In an ideal world, get a posting to somewhere with turbine twins or multi's and fly these as much as possible. You can count your hours, especially if you also get the ratings i.e. night, multi, IMC/IR. Get QFI's to sign your log book as often as possible. They are Instructors even from the CAA point of view as well as the potential employer. Remember, this is worthless if you don't already have your PPL as a minimum. Book everything you do but don't lie (Parker hours etc). It will come to haunt you down the road. Try and record also your multi-crew co-operation training/MCC etc. It is relevant. Seat drills and the pool probably arn't.
At the (same) USA based JAA school, get your CPL/Multi/IR. Oxford are good, but will cost much more and take longer. And remember, time is serious money. Oxford is OK but only if you are part-sponsored really, and there isn't much chance of that. Which ever way you go, you will start to gain more contacts on the way. Most, but I believe not all, commercial training requires the candidate to be a PPL holder. The Military Aviation scene is small. The 'big civvy world' is also a small place. The word gets around pretty quickly, and that doesn't include pprune.
Believe me, without CPL/Multi/IR as a minimum, you won't even get a foot holding the bottom of the ladder, let alone one on the rung. There are an awful lot of kids with ATP/frozen ATPL's out there at the front of the queue with good hours, cheap to hire and easy to mold into the company frame of mind.
If you can commit yourself to the above suggestion, you MIGHT make it and, seriously, good luck to you. If you think it is too much to contemplate, consider another direction.
Sorry to go on and I hope this doesn't sound negitive, and the very best of British to you.
camlobe