...should I spend £100 quid registering as a RTF
Introduction of the CAA £100 charge and it's daft room configuration requirements for registering as an RTF was the (fully intentional) beginning of the end for small (one peron band) flying schools.
There must be SOME legit RTFs where the principals simply wish to retire and new blood could take over - why not seek out one of those and buy it out?
Nope. I know of an instructor who tried to take on the RTF of the flying school he worked for when it was about to close down, but the CAA wouldn't allow it.
MJ