As someone who does Bio and Chem A level + AS physics, I would strongly advise you take maths tbh (just my opinion!) because otherwise you will have to teach yourself topics like logs etc which aren't covered at GCSE but they assume you know since most people take maths alongside. Also there is loads of maths and stats involved in biology with a large overlap with A level maths. For example, hypothesis testing which we spent 3 lessons learning in maths and only half a lesson learning in biology, so it is quite hard to follow if you're not doing maths alongside it in my opinion.
This is obviously just my opinion and many people take these subjects without maths and do just fine! Personally though, I dropped physics because maths was much more helpful and complementary to Bio and Chem! You could also consider taking something like core maths alongside your 3 a levels just to keep up your maths skills if you don't want to do the whole a level, but tbh maths gets a lot more fun at a higher level (especially compared to GCSE!) especially with mechanics etc, so if you like physics, you'd probably really enjoy A level maths!