I'm not familiar with the auto-entrepreneur scheme, but when I first started teaching free-lance in France, I formed an assoc. 1901 to enable me to get a SIREN and SIRET, operate legally, declare for tax exemption, draw up an employment contract for my secretary, and contribute for my own SECU. Most of the private customers were not interested in a contract, but they got a computer printed course description, invoice, and receipt - pretty much the same as is practiced in any high street cram school anywhere in the world today. Under the formation professionnelle/auto-entrepreneur are you expected to submit the contracts to a government department to obtain a subsidy or something? I would be more inclined to do the TOIC stuff for the lycéens on the side.