Every ATCO in here seems to think that they work for the worst employer. Not everyone can and there's more to life than work.
If you can go to work, enjoy it while you're there, get paid relatively well, go home and enjoy your life, wherever that may be, what more could you want? There's always the "grass is greener" but you only get one go at life so grab it by the balls and live it!
NATS has its problems as does every other ATC provider, be it SERCO, AIRSERVICES AUSTRALIA, NAV CANADA or any other that I could mention. You're in a privilaged position to be able to use your qualifications in more than one country, if its what you want, take your chance. If it doesn't work out you'll more likely than not, get a job with your old employer!
Best of luck to any that cross over.
Let us know how you get on!
(Edited to correct the spelling of an ATCO!)