Any instructor who is Self Employed must be working for more than one establishment,not necessarly in flying.The tax man will not allow you to be S.E. F.I. working for just one club.Also he will ask you what you are providing,just your services is not enough.Maybe you can say you provide maps headsets etc,there was a case recently of a self employed piano teacher who provided her services as a teacher and nothing else.Clearly not practicle to cart a piano arround with her.Tax Man did not like it.As for myself I was told by inland revenue I must work for more than club to qualify as S.E.Well thats only my personal experience.