How much can you earn as a horse riding instructor?

It relies entirely on the circumstances. If the riding school charges a lot of money for lessons then they will get enough money I think, don't you!

But some of the money has to be spread out to all the staff and for new equipment for the yard. So Id say about £70-75 in 5 days.

Well, at my Mum's riding school, each member of staff is payed 40 pounds per day (this applies to weekends only) to work from 8.30-3.30 as an instructor/escort for rides. They also have to work the yard with about 4 other members of staff and voluntary helpers. This stables is quite cheap though so it depends as to what stables you are at.