I sympathise with people wanting to drop out (not just because they cannot be arsed though) I really do.
However, there are a few unis, and I really mean very very few where getting an offer of study is something that you cannot turn down.
They are, not exhausitively - Oxbridge, Yale, Harvard and in my opinion the best place in the world, MIT.
Even if you don't like the look of these places or don't find them much fun when you are there, you just stick at it if you can.
I know it sounds stupid, and goes against the "follow your heart" mentality but this is a rare case. Bristol is a good uni but not in the same league by any means.
So what if you have 3/4 boring years. You are going to have to go into the real world anyway where you will spend circa 40 years working jobs you hate - so get used to it.
Exceptional circumstances call for exceptional stiff-upper-lip-put-up-with-it-ness.