Bath Or Southampton For Maths

Got Offers from both Bath and Southampton Uni to do maths this year. Bath is a 3 year degree while Southampton is a 4 year masters.
Bath entry requirements would be A*AB for me as I'm doing AEA. (A* maths A further maths)
Southampton would be AAB, with AEA. (A maths)
Bath accommodation is very expensive, and I don't get much as a maintenance loan. Whereas Southampton is significantly cheaper
I regularly do bouldering at the local climbing gym and i know that there isn't one in Bath but there is one in Bristol, whereas there are a couple in Southampton.
I don't drink and haven't really learnt to drive yet.
I love maths and have done for years so I know this is what I want to do.
I can see the pros and cons of both but can't decide which one to choose.
If anyone does either of these courses your input and advice would be amazing.
Thanks