I took the leap last year
After 22 years I was lucky to get a place as an ATCO. I was offered a course in Wales and Serco paid for it too-I was lucky. If you are in your twenties I would go down the NATS route as your future earnings and career would be better overall. If you are like me and not to fussed about setting the world alight then self funding/sponsership thru one of the ATC schools is a great way into it. After all you can always try to get into NATS at a later stage if you fancy it, they advertise for jobs around the country at regular intervals and I know lots of people who now work for NATS that started for other ATC service providers. After only a year I know earn what I earned in the RAF and with my pension I am better off financially and in my private life ie no secondary duties etc just the gardening lol . The only down side really is the commuting which many service people may not be use to, but you will get use to it. Civil ATC is slighty different from Mil but not so much that it is a problem for someone who has the right motivation. Good luck