Deep Float......have e-mailed you with some details.
TAG Aviation:
http://www.tagaviation.com/
I would suggest that you phone ATC Recruitment at CAA House in London. I don't know anyone who has had any success with the website application!
Speak to Directory Enquiries. NATS new address is One Kemble Street. They have seperated NATS from the CAA address which is 45-59 Kingsway.