i gave up drinking for 4 years
Not sure that’s good advice, I couldn't think of a worse time to give up drinking than at university, its one period of time in your life where you can get drunk very cheaply!!
You can't go wrong with accountancy, I started off down that route after doing a maths degree, but ended up packing it in for a job in one of the city banks doing something quite different. If you are prudent and do get a half decent grad job in accountancy I reckon you'll have saved up the sufficient funds by about 25/26 rather than 28/29.
Good advice on the student loan though get that out of the way asap, however if you follow all quants advice I suspect you might go insane, I was what he refers to as a "lazy ass" student- never did me any harm.