Business studies is based on businesses and economics is based on the economy as a whole although there is some overlap hence many degrees are combined business economics. Most suitable for accountancy? Neither- skip the uni part and go straight into a trainee accountant position - you have to do at least a 3 year accountancy qualification regardless of whether you have a degree or not - so why not avoid all that student debt!
Thats what i did anyway!
I'd look at websites for the following: AAT, ACCA, CIPFA, CIMA as they all offer accountancy qualifications which you can study part time while working. They are basically all practical, vocational qualifications for an accountancy career, while a degree in accounting doesn't actually train you to double-entry bookkeeping (for example!)
Do the Diploma in Certified Accountancy. Its a 2 year course run by some Universities, which you do after A'Levels fulltime and this will get you exempted up to the last 4 exams of ACCA (Certified Accountants exams).
You will then have the 1st of the last 4 exams to sit by itself.
The ACCA exams are now pass one keep one basis I think, therefore you wont have to pass final exams altogether. Any you pass you keep.
Therefore you could get a job after the 2 year fulltime diploma and then qualify in a further year.
Rather than doing a 3 year degree then having to do professional exams after that.