The web link to Gamston is here:
You can have a look and see what it does, the contact details are on there as well. If you want to visit air traffic control specifically, then you could write to the airport manager and explain what you would like to do, what you are thinking of as a career and ask if a visit to the ATC could be arranged. You will need to take a responsible adult with you and it would be worth putting that into your letter, so it shows you have thought about that aspect. I’d still suggest talking with your OC and finding out the details for your Wing Aviation Officer, asking if you can contact them directly, or if OC would prefer to do it themselves.
As far as Gamston goes, it may be worth suggesting a squadron visit to your OC, it may be something one of the staff can pick up and organise. Numbers are often limited (Doncaster ATC limits this to 6 cadets plus staff), but there may be others on your Squadron who would like to visit as well.
If there’s anything else you would like help with, just ask and good luck!