I know so many people who do NO WORK (and I mean I have never ever seen them actually studying or talking about studying, or planning to study, or seeming mildly interested in their course at all), and they still pass. It is possible, particularly in science/arts degrees where you needed to get a fairly good UAI/ENTER to get into the course in the first place. Because of this most people can probably pass just on basic intelligence and a few hours of crammed study before exams or assignments.
However, I think some people will regret it when they get out of uni (perhaps not in the science/eng/finance field where there is lots of work, but certainly in the Arts/Humanities field where there isn't so much) and find that employers are looking for people with a better average than pass.
I try to study well - sometimes it's hard to stay motivated when others seem to do no work - because I want to get into internships and get some good work in a competitive area (politics/international relations) when I finish, and if you do a bit of work it isn't that hard to get mid 70's percentages. Over 80 is virtually impossible in assignments, but 70's is generally as high as employers are looking for.
I certainly don't get around to doing my many (boring) readings every week (Unfortunately I'm not that interested in research - I'm more of a hands-on person - which is a bit of a problem doing arts...) and naturally my essays are generally rushed (because NOBODY gets their essays done more than a few hours before they are due at uni!), but it's easy not to lose silly marks by handing things in late, or simply not doing little assignments (3-5 percent of your total mark for the subject), because the marks you lose for this can add up..
IF you get everything in on time and relatively well researched/written/thought out, you'll be okay.
Naturally, per week study depends a lot on course/uni etc - in Science a lot of the work is done in class because they have a lot of contact hours, and pracs etc. In arts, there are only around 12-13 contact hours per week, but a lot of reading and research to do outside of that.
In terms of finding fun - join a club! Ie. debating club, music club, beer club, chocolate club, pilates club whatever. They are fun/social, there is generally a lot of drinking, and it is way easier to make friends if you find an environment in which you actually see people on a semi-regular basis, because in actual classes/lectures you rarely see the same people, or only see them once a week.
Hope this isn't too long...