I am in a similar position to you. I got the grades that you are predicted for GCSE last year and take the same options you want to the, but do Spanish instead of mandarin. I want to go into the financial industry which I assume is similar to yourself. I wouldn't recommend doing a language unless you have a genuine passion for the language, country, and culture itself, rather than doing it for business purposes. I find that these are required for the motivation required to succeed at doing a language at a level. However, the other options are amazing. Physic and Further maths are a challenge which I personally like, and economics is interesting but very hard due to the essay style of writing. Good luck with your GCSEs