I suggest that you write all your subjects out, and arrange them in terms of which you enjoy most.
Biology a level is anything but boring, you learn about immunity, cells ( oh I love cells), the heart, courtship, etc. It's an interesting challenge !
Chemistry a level is one of the hardest, my friends say it is harder than maths and furthermarhs. For example, in FM mock, people got A*s, chem highest was a C. But obviously that changes as exams come closer. It's hard, but if you work at it you can still do well
Physics needs good maths skills. Don't consider it if you can't handle maths! If you can, great! You also need to deal with challenging concepts.
French is a really good choice, shows some variety ! Do french, it's respected, it's great! It can help things like law, finance etc.
Maths and F maths are hard. Loads of people drop out each year. People with As. So I'd say don't consider maths unless you got a high A/ A*m and don't consider further maths unless you found maths gcse a breeze.
Have you considered geography? It's a little lighter than the science A levels, but equally respected. If you did French, Maths, Geography, economics that would be good variety.
Equally French,Chemistry, Economics and Maths would be good.
If you feel you can cope, you could do maths, chemistry, biology physics. But people who do that tend to get A*s in all 4 at GCSE.
Only do further maths If you really love maths.
If you're good at any humanities, bring those in for variety. Maths and history/ english lit is a great combination to show mental agility. You don't want your a levels to be too homogenous.
Good luck, and don't stress, do what you will enjoy and what you're good at. Also, if you have a paticular course in mind, check the unis requiremnts