The flying school I assist at we currently pay:
£25 per block hour
£20 per ground school hour
Nothing for long (ground) briefings.
The plan is to move this to £30 per flying hour and £10 per hour for long briefings at some stage this year.
We have increased flight training prices in 2019/20 for the first time in a couple of years. The likelihood is we will try to keep instructor wages increasing by inflation each year from now on.
We have an open and honest dialogue with our students about the difficulties of retaining instructors, and therefore the need to attract new instructors otherwise there won't be any flying school at all. Fortunately our students are mostly over 25, and have a lot of appreciation for the need to pay instructors a fair(er) wage.
Personally, I still feel that £30 per hour is far below a fair wage, but much more than this and as others have said, very few new students will sign on.