There is not a lot you can do with an ATCO qualification and no medical, on the other hand there's a lot you can do with a teaching degree and no medical.
Also you don't know if you still want to be an ATCO in 10 years time.
I loved my teaching job when I started, and that was only 4 years ago.
Ricky if you have a PPL you shouldn't worry too much about CAP493, or pre college studies... In my many visits at the NATS units I always mentioned I had a PPL, to save them from explaining basic things but they still thought I wouldn't know how to read a METAR etc etc... I know some PPLs have shocking R/T because they never get away from their comfort areas, but if you get frequently in and out of CAS the whole R/T subject shouldn't be too much of a problem.