If you want to study Arts and Social Sciences, go to MI. If you
study hard, get a good A-level certificate with some As and Bs, and
a good GP grade of B3 and above, it's easier.
However, if you're going for business/engineering related
disciplines, I'd suggest you head to a Poly, but make sure you're
in the top 5-10% of your cohort, then when you go to Uni, you can
skip a year or two. It depends.
I'm not from an Engineering background, so that's all I know about
that.
Of course, if you want to save money, just go MI Science and piah
your way through and be independant.