These days Oxbridge will likely expect 4 A-levels anyway, and they're happy for you to have your 4th be an essay subject.
(I got into Cambridge Maths-with-Computer-Science with A-levels in Maths, Further Maths, Chemistry and French, albeit with a raised eyebrow for not doing Physics.)
no subject
(I got into Cambridge Maths-with-Computer-Science with A-levels in Maths, Further Maths, Chemistry and French, albeit with a raised eyebrow for not doing Physics.)