From an Area perspective, it may be 11/12 months (as it is currently) but that's to achieve your Student license. Then you go to your unit and do OJT to earn your validations which will take another 12-18 months, something that's not noted particularly clearly on the NATS Careers site.
As a trainee controller 1 month into his Basic course at the moment, I don't expect to be "going it alone" for at least another 2 years at a minimum...