The preliminary contract becomes automatically binding after 7 days, at which time you will be required to pay your deposit as agreed, and withdrawal of the buyer at this point will be at their own cost as they will lose the 10% deposit, according to suspensive clauses. There is a clause which can offer more protection towards the deposit and allow the buyer to, under certain circumstances, ensure the return of their deposit. An example of suspensive clauses: an unsatisfactory "plomb" (lead) survey, a French loan not accepted, an unauthorised extension by the local government, etc?