But seriously OP, do whatever you like (within reason - no football studies pls) but make sure to get the best grades possible this year. Aim to get into one of the targets (Oxford, Cambridge, LSE, Warwick and Imperial) or semi-targets (Notts, Durham, Bristol, Bath, Cass B-School etc).
In terms of importance:
Uni attended > Uni course
If you want to do something quantitative (i.e. exotic derivatives, algo trading) I'd stick to the Mathsy courses: Maths, Physics, Computer Science, Engineering etc
Otherwise, whatever tickles your fancy. Could be History, Econ, Finance, Psychology, Languages - any old, traditional uni subject.
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