You can apply for lots of business related courses at university, you could even apply for other subjects if you wanted to. Look up on the university websites what they typically want, you can also call up some universities and find out what they'll allow you to do and what grades they'd ask for. You can also apply for foundation years at university for different courses. Foundation years (as long as you pass) let you on to study other subjects at university, they can also be a good way of transitioning to university too.
Note that you only get 4 years total of student finance for undergraduate degrees, but that's okay as a foundation year would be included in that if you wanted to go down that route.
Most universities look at what you got for level 3 more than GCSE (though they still take it into account) so if you decide to choose a different course for level 3 make sure it's in something that you actually want to study and that you think may lead to a good career.
I'd highly recommend that you do some relevant work experience when doing your level 3 course if you can at some point, this will help your application when applying to university. When you start university make sure you do placements at different places too (summer placements or a year one), this will help you when applying for jobs.