Do both – there are *lots* of affiliates who are at Uni.
How intensive is the course? I am sure that you will find plenty of time to build sites and work on your affiliate stuff – and you might even discover new niches through your learning.
Your studying will be something to fall back on – even if you dont go into the Finance industry and work in a smelly office, it will show you have the capacity to learn, which will be a major help in whatever you want to go into.