Protection when paying by credit card comes from section 75 of the Consumer Credit Act 1974; it makes the credit card company liable to the customer for any breach of contract or misrepresentation along with the supplier of goods and services. If the school goes belly-up, they become liable. Protection for purchases outside of the UK is a grey area and it only covers UK issued cards. It does not apply to regular Amex cards as they are Charge Cards – paid in full every month.
Also handy to know for any purchases outside of aviation!