Graduated from Warwick last June, Biochem. Biochem and Biomed have 90% same modules in Year 1 so I can help.
The Life Science department is probably Warwicks more quiet dept. It doesn't get the recognition like Maths, Economics, Business etc do but its a very good department in terms of tutors, campus, student support, as well as the actual Biomed course.
Best part of the dept is that the tutors, from my experience, were VERY very flexible and supportive with students regarding COVID issues and other things throughout my degree. If there were problems with students, I found they were more responsive and found solutions faster than other depts in the uni. I felt the tutors genuinely cared for the bio students - this might be something you should consider, assuming there will be more issues about studying/covid/flexibility etc that might come about when you join.
In terms of which uni has better reputation for life science - doesn't matter that much if you find a career in an unrelated field (I'm in finance). If you want a career in research/med, just get a 1st + work experience. Warwick is a good uni enough uni. KCL is generally a more reputable uni though (probably internationally)