Heyy,
Admissions tutors would look at your grade before the type subject you have taken so I would recommend choosing a subject where you'd get the best grade. Granted it does look good having more breadth of subjects, but that won't matter if your grades aren't that good. If by taking rs or english you could get an A instead of a B, i would recommend switching.
Also, if you don't enjoy bio then that's more reason to change it. If you enjoy what you study, you'll do well. It's no point being miserable for two years.
Does that help in any way?