Ooooh heck, Maths, further maths, physics and chemistry is a heavy load, although to be fair maths and further maths togetherwork well. I don't know about further maths, but I don't think there's any coursework for maths.
Physics I have no knowledge of, Chemistry doesn't appear to be too time consuming as far as my daughter is concerned. Although I think the first exam in January is a bit of a shock to the system...she didn't do so well in that one, and is resitting it in this coming January. (She's in year 13 now).
She also does History which didn't have any coursework (I don't think) in y12, but has a piece of coursework to be in around Easter in place of an exam for half the A2 course, so if your son doesn't like c/w this is quite a big chunk.
My older son took Philosophy and Ethics to A Level...this is not a soft option at all, and is equally as diverse as history would be to his other options. Again there is a piece of coursework to be submitted as a part of the final A2 but if you don't do so well you can retake it in June as part of the main exam (not sure if this is the same in all exam boards, it's worth checking). I think it was a very good choice of subject, you have to display good argumentative skills (
) along with very good essay writing etc, which would demonstrate a different ability from the maths & science based subjects he is taking.
French A Level, I have no knowledge of either, so can't advise.
Economics, I have no knowledge of but would suggest it's another subject with a mathematical bias so won't necessarily show off different skills.
I think he also needs to consider what he wants to do at University...that might change his opinion of which subjects to take into 6th form
I hope this helps.