In France the legal side of a property transaction is carried out by a public notary, these perform the role of solicitors in the UK with the main difference being that the "notaire" would normally act for both the vendor and the purchaser with fees set down by the government. This reduces the amount of legal correspondence speeding up the whole process.
It is possible to use the services of a UK based solicitor specialising in French conveyancing in addition to the French notaire. Fees vary depending on the solicitor and the nature of his involvement.