You need to send your original birth certificate (the one with your parents' details on, not the little orange version) along with the translation form to this address:
M. Laurent Batut - Conseiller Culturel Adjoint
Service culturel - Ambassade de France
23 Cromwell Road
London SW7 2EL

Send this envelope by recorded delivery and enclose a self-addressed recorded delivery envelope so they can send your translated birth certificate and your original certificate back to you. Click 'Read More' to see how to translate your birth certificate