Louis
An admirable career if ever there was one, a fine choice. But don't limit yourself to looking for work only in the UK, the wonderful thing about the job is wherever you go in the world the operating language is English, and the job requirements don't change too much. I took the step to move abroad at a young age, and now work, as Wigglet describes it, "less hours for considerably more pay."
Try looking under the jobs section at
www.eurocontrol.be and see for yourself.
Of course money isn't everything, and ATC is a truly rewarding career, I know very few people outside my job who can honestly say they enjoy what they do and get a kick out of being busy.
As far as preparation goes, I agree with all the advice from the previous posts, basically familiarise yourself with ATC worldwide, visit centres, at Manchester, Swanwick, your local airport tower, whatever, and get talking to people. Otherwise the practical side of being a controller is something people either have or dont have, that "x factor". All you, or anyone else can do is your best.
I wish you all the best in your applications, and who knows I may be working with you before too long! Let me know how you go.
Good luck,
fourthreethree