Leeds is a great city and a wonderful uni. However, Birmingham is equally strong both as a city and as a uni. As others have written look at the course content, which one interests you more?
The Leeds programme does look interesting - choice of 3 topics from biochemistry, biology, chemistry, environmental science, food science and nutrition, mathematics, and physics, specialising in two of these in years 2 & 3. It means you can still do biochem if that floats your boat but you can delay the decision for a year.