I get paid £0.00 per hour for flight instruction.
I teach on the ground for free.
I charge that miserable fat barsteward Gordon-the-grasping 40p per mile for any mileage involved with anything to do with being a UK/FE PPL.
I do charge for Flight Examining - at the going rate. It covers the cost of 6-monthly medicals and my revalidations - but that's about all.
I charge nothing for ground exams or debriefs.
I have had a career in aviation and now I'm helping others to do the same.