From the perspective of someone who was in your predicament this time last year, I would counsel you not to study Accounting and Finance if your career aspiration is in Investment Banking. I was actually intending to study Accounting and Finance myself. Fortunately my dad went to uni with many people who are now in senior roles at Investment Banks, so I spoke with many of them.
No word of a lie but they all advised me against studying A&F - IB's don't respect it, they treat it like a Management degree. Its seen as a very 'soft' and 'weak' subject. A&F lacks the comprehensive education of financial markets, investment theory, econometrics...
Economics was the main degree they suggested. However, Economics wasn't a course I wanted to study as I didn't do it at A-Level and from research I gathered that previous education in the study is a must otherwise it is very difficult at uni.
One of my dad's friends is an Equities Portfolio Manager at Goldman Sachs so he has the last say before recruiting a trader into his trading desk/team. He said that another highly preferred course is 'Finance BSc' (I was told that LSE and Cass offer this course), it caters a lot more towards Banking careers as their modules are much more focused on Investment practises, money management and risk...
Pending my A-Level grades this August, I will be studying Finance BSc at Cass. I hope it doesn't seem as though I'm trying to brainwash you but these are just my experiences and thoughts.
If you want a career in auditing and accounting then pursue Accounting and Finance; but if its a career in Investment Banking, you'd be better off straying from the course.