As above, 4 A-levels isn't required. However, more generally, Geography isn't a requirement for most courses, so doesn't add that much. Even if you were specifically interested in Earth Sciences (using the term broadly, i.e. not just geology but also oceanography, climate science, environmental science, etc, etc) it's not a requirement, although can be a useful way to explore the aspects of the subject. You could do an EPQ similar to the Geography coursework (in more depth of course) on some physical Geography/Earth Sciences subject which is less likely to "overload" you than taking Geography itself.
Further Maths is very useful for Maths/Physics/Engineering, and for other physical sciences is reasonably helpful but not required by any real means. If you're considering something like Geophysics (or pursuing a Geophysical path in Earth Sciences at Oxbridge) then it'd be worth taking, but otherwise you will probably catch yourself up reasonably without it and should only take it if you actually particularly enjoy and are good at Maths.