First place to have a look is here;
http://www.natscareers.co.uk/
Not the only ATC provider in the UK or the only way to train but an excellent starting point.
If you do enter ATC you will be doing a lot of learning both practical and in the classroom so if a learning environment is a problem for you it may not quite be the career you were looking for.
18 is the minimum age for entering and I would recommend you continuing with your education up to 18 however if it is what you want no degree will help change your mind.
The actual NATS college is in Dorset as I note you are.