Currently doing both at AS and I only really suggest doing Biology if you have an interest in it as you'll develop a strong dislike for it if you don't. I agree with what is said above also, I find Biology much harder.
Ultimately it's down to what you think you'll do better in if Loughborough is accepting either as a requirement, but be wise, you don't want to be doing something you don't find interesting for 2 years, as that'll just lead to a worse grade due to lack of motivation to revise.
I wish you the best of luck with whatever though.