When I joined as an RAF ATSA (FOA nowadays) it was always possible and a fairly natural career progression to become a SNCO controller if you passed the aptitude tests.
I think that in reality traingin to be a controller still happens - though I would have thought that 4 years is a bit optimistic for the masses. Also, as a FOA you may find yourself in station Ops or Sqn Ops as opposed to the tower.
Good luck