A levelsWatch this thread
Essentially, you just need to pick a school or college which accepts private candidates - see https://www.aqa.org.uk/student-and-p...ool-or-college for example.
The issue - as stated at https://www.aqa.org.uk/student-and-p...ate-candidates - is that "Exams are not available for private candidates to sit outside the UK." So you would have to travel to the UK to sit each paper, it seems. Is that feasible for you?
For the other A level exam boards in the UK see:
Do you know what exam board you'll be using? It's worth reading through their "private candidate" pages (see above) for all the details.
(Note that CCEA refer to a private candidate as an external candidate, but it's the same thing.)
(If you want to sit them, it would be easier to sit International A-levels since you can take them in France.)