I'm not sure that I'd describe the job, as I'ERIC so elequently puts it, as a piece of piss.
There's no doubt that it's an excellent career, well paid, lot's of time off and I wouldn't willingly do anything else (short of being paid the same amount or more for doing nothing), but it's also an extremely responsible job where you have to make instant decisions and they have to be right every time.
Don't underestimate the intensity of the training programme both at and after college or take your eyes off the fact that you can be chopped at any time during college or field training.The ATC training is very hard work and coming into the college environment with your brain still in "information acceptance" mode is a big advantage.
Although I didn't have a clue what I wanted to do when I left college, I felt much the same as you, with the benefit of hindsight, I would suggest that you at least finish the two years of 6th form and achieve the highest grades you can, then explore the various options - NATS, starting an ATC career at a regional non NATS airport or Eurocontrol.
Until then, it may be worth your while trying to get a part time job as a "hanger rat/ person Friday" with one of the many flying organisations in the area, you'd get invaluable experience of the workings of an airport and either be paid and/or get some flying experience.
All the best anyway.