Savechip,
I agree with all of what 'anotherthing' has said in his reply to you.
I made the transition across from mil to civil in 2003, on the airports side, at the grand old age of 38. Many of the ex-mil guys/girls who did the course at the same time were of a similar age. As I recollect, the vast majority of the folks that went through all passed and the vast majority validated at their respective units - mainly Aberdeen. So the age argument made by HR and others against ex-mil ATCOs, on the airports side, is frankly a load of bull. That cannot be said of the area side and I cannot argue against those on the dark side who say that ex-mil people have really struggled - they have. But in not continuing to recruit ex-mil folks on the airports side, NATS is only harming itself.
On the subject of money. We all had to self-fund to a greater or lesser degree and were all prepared to make that financial commitment to our future career. Yes it is expensive and yes it is a big ask of someone who is used to a far larger pay packet and may have significant family/financial commitments. However, you don't get something for nothing in the outside world and NATS is no exception in this.
In short, I would keep banging on the door, because sooner or later NATS will/might wake up to the fact that they are short of numbers on the airports side. Gonzo might be able to shine more light on where those shortages are most acute?
However, if you do get picked-up by NATS, be prepared to tighten your belt, because it ain't cheap - but it is worth it.
WJMcP
P.S. Top tip to all ex-mil ATCOs. If you get accepted by NATS, shut the f... up about what you did before, face the front and get on with it
You will impress no-one with the big I was....