It is however the case that on my trips around Europe I see a lot of very nice airports which would not be there if all planes landing were "hang-gliders with a lawn mower on the back"
IFR GA is what keeps the facilities up, and what keeps the training system going.
Notwithstanding that the vast majority of the pilots never proceed to IFR capability, eliminating this would push GA into farm strips.
but does anybody know of a single list of UK airports with GNSS approaches?
I am sure it has been posted, but for a start, and taking "GA" ones only:
Lydd
Shoreham
Gloucestershire
Blackpool??
There are others e.g. Gatwick and Heathrow but they are not relevant to GA.