WWW Nice thought, but how long would it take for your local tax man to cotton on to that - don't forget your next pupil could be one!
How about a scheme whereby the school hires the punter an aircraft at the going solo type rate. The instructors would all name their own price to the punter, and the punter could choose which instructor/price they liked. All money goes through the payroll to avoid tax man related problems. That way the school does not have any instructor costs, (it would deduct the Class 1 NIC from the money) and the instructor can earn whatever they like to charge.
Ends all the arguements about greedy fat cat school owners.
Simple.