Definitely maths if you can, computing, and maybe Physics.
That said, a lot of the unis I visited (Durham, Birmingham and Warwick) expressed a lot of interest in worded analytical subjects along with Maths (English Lit, History etc.) that prove you can actually write coherently/logically in something other than equations or code.
I assume it's not 'expected', but if you can't afford to fill out all your choices with maths and sciences and need a humanities subject, go for an analytical one over anything else (I'm doing History at A2, and that forms part of my offers for CompSci/SoftEng)

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