Chemistry is definitely the odd one out there. I have to ask what makes you want to study chemistry? If you are using it as a way to keep your options open, you should be aware that most science courses at university level would prefer 2 sciences (e.g. chemistry plus biology, or chem plus physics, etc). You may find that it doesn't really "mesh" with your other subjects -- sociology and creative writing in particular.
I'd say that biology is a better subject to have if you choose to have only 1 science. Geography or geology may be good options too, or environmental science, if you would like to study a single science subject.
If you want to study at an RG university, the main thing is to choose subjects you feel you can work hard enough to get the A grades in. It's okay to have 1 or 2 subjects that aren't necessarily so facilitating.