Hello Mamabear,
Oh yes, I remember reading your posts a few years ago on the Birmingham thread!!! Waving!
Maybe check if his school uses Activelearn as listening to texts spoken with the proper pronunciation will enhance his learning and help him the day he will sit the listening paper.
Do also check with your DS if his French teacher has not posted anything on the Moodle site of his school in the French GCSE section. It is funny

(and sad!

) how some students (some of them excellent!

) do not take the time to take this obvious step.
If you have yourself learn French when at school, maybe drill him on his vocab and, if possible, keep this going during the coming academic year. Learning vocab is - I think- the most boring part of learning a foreign language for a 15 years old.
To learn conjugations, he might find that listening to some of them on youtube may help him.
And of course, you have some resources published by CGP, like
- a Complete Revision & Practice AQA
- GCSE French vocab tester