CJ... It's not a matter of NATS "covering training fees". If you are accepted for NATS, that's your employment and training is part of it.
I don't think things are too rosy in the RAF at the moment - take a peep at the Aircrew pages on here and you'll see fears of redundancy. Unfortunately, recruiting in aviation always follows a Sine wave - everyone goes bananas and recruits like made.... a few years later the units are teeming with staff so they stop recruiting..... until well after shortages occur.... then they get going again. It's been like that as long as I can remember - back 40+ years.