UPDATE: OK, so I have managed to replace Sociology with Geography.
I have also spoken to my parents, and they have said that if I really wanted to, they would be happy to fund for me to spend my 3rd year doing A-level mathematics on it's own (basically private candidate). They also said that if my A-level results are very very positive, they may allow me to do a second one along with this (physics?), but I personally doubt this will be the case.
Basically, after doing research, any Uni with a ranking of roughly 40 and below will accept you without maths.
I wouldn't say that physics is an essential requirement, but it is definitely a useful one.