Capt.H. I hope I haven't doubled up on this thread as I am having trouble knowing if it is transmitted. Re glide approaches in the 152. The extra speed advised by your RAF instructor seems at variance with the recommendations at page 4-21 of the 152 POH.
Personally I see no problem with 54k at flare from a C152 glide. Heavier trainers such as the Harvard (in the good old days) certainly required a higher approach speed on a glide approach to allow for inertia at round-out. But I don't think that you can tar all trainers with the same brush, unless there is a specific technique for glide approaches in the manufacturer's POH. But with your CFI and Engineer chappies glowering from the crew room, maybe you would be wise to add a couple of knots to make sure you don't sprong in at the flare. Good luck!