I cannot ever remember airmans married quarters, even those designated as WO quarters, with garage attached.
I lived in Blenheim Crescent in Ruislip back in the 70's in quarters just like those in the movie and, yes, there were some semi-detached quarters with attached garage exactly the same as that shown. They were meant for Flight Sergeants and Warrant Officers but the one next door but one to ours was occupied by the AOC's driver (a corporal) and he would bring the car home at weekends, wash and polish it, and keep it in the garage on standby.