EASA rules allow the French, and any other State that has the mind to do it, to train for the Brevet de Basse en route to a LAPL.
Reg 1178; Article 4
7. A Member State may authorise a student pilot to exercise limited privileges without supervision before he/she meets all the requirements necessary for the issuance of an LAPL under the following conditions:
(a) the privileges shall be limited to its national territory or a part of it;
(b) the privileges shall be restricted to a limited geographical area and to single-engine piston aeroplanes with a maximum take-off mass not exceeding 2 000 kg, and shall not include the carriage of passengers;
(c) those authorisations shall be issued on the basis of an individual safety risk assessment carried out by an instructor following a concept safety risk assessment carried out by the Member State;
(d) the Member State shall submit periodical reports to the Commission and the Agency every 3 years.
My suggestion is that she go to a French school and complete the rest of the LAPL training; that will then be valid in the UK. Don't waste your time asking the CAA; that is not their function any more, they probably won't have a clue, and will simply produce more meaningless drivel.