First of all, I agree with Fidgell - relax!
But if you are really keen to get some kind of experience/knowledge beforehand, why not approach a local airfield or two and enquire about work experience? If the unit is full ATC so much the better. I see from your post you live in the Southampton area, so Shoreham may be worth a bet.
I started my ATC career at a small local airfield and found the experience invaluable.
That's my tip.
Good luck in your chosen career. You'll have a ball!
Foxy.