chemical engineering requirements

Uhh, chemistry, physics, maths...?

I did.. most of universities require chemistry, maths and the third subject a science so I was wondering which one would be preferable physics or biology. Obviously it would be physics but I would much rather take biology

As above, the usual requirements are Maths and on of Chemistry or Physics. Some courses require both Chemistry and Physics, and some require one or the other specifically. If it isn't otherwise specified then any subject is suitable - although I imagine STEM subjects would be preferable.

Given the intersection between Chemical and Biochemical/Biological Engineering and Biotechnology, Biology is a fine choice and may be particularly appropriate for some courses. Do of course check individual course entry criteria and if in doubt, contact the university to clarify.

You may wish to consider taking Further Maths if it's available, which is also extremely useful in of itself, and taking additional mechanics options if available can help ameliorate the lack of Physics (this latter point especially, although to some degree generally as far as FM is concerned, is less of an admissions consideration and more in terms of actually coping with the course content once you begin).

I would note, Chemical Engineering is relatively little "chemistry" as you may see it, and much more mathematics and physics (specifically fluid dynamics and thermal physics). I make a point of this as it was noted to me by the then head of admissions for Chemistry at Southampton that they (at least used to) get a number of applications every year from students who start Chemical Engineering then realise they actually wanted to do Chemistry because it is, as above, mostly "not-chemistry" other than physical chemistry aspects and some basic organic chemistry taken earlier in the course.

I’m currently doing chemical engineering at uni, at my uni they make you take a course in both biology and physics, the physics course is at a similar level to a level but the biology is very basic. I would strongly recommend taking physics since a lot of chemical engineering is mainly physics (thermodynamics and pressure etc). For chem eng the chemistry is fairly basic but you need a strong knowledge of physics and very capable mathematic skills. In general actually biology isn’t used, it is mainly the chemistry of biological reactions and therefore not much biological knowledge is needed. However, to get into a chem eng course in the first place you need good grades, so if you think taking biology at a level would give you a better chance at getting in then take it, you can build on your physics when you’re at uni, but if you’re just as good at both, definitely take physics as it will make it a lot easier for you at uni.