If u learn (copy down lecture notes and listen to them) and do ur homework, and understand whats going on u are sure to get at least Distinction. But if ur lazy like me, and try to catch up ur homework and missed out stuff 10 weeks later, the best you can get is prolly a credit. it also depends on the difficulty of the subject.
Also, 50% or more of the mark depends on your finals. If you fuck up your final, a second chance is given called supplementary exams. If u pass this, the highest mark u can get is "pass", regardless of what you got in the assessments.
About lectures themselves: Most ppl cant be fucked to attend lectures because what the lecturers do could be called 'ranting". Most of the time they tell u useless stuff thats of no help. But, if u listen to the rant, ur most liekly to perform better than those that skip out on the lecture.
You are allowed to talk and have fun with ur friends, but if the noise level gets too loud, the lectures stop dictating their stuff for several minutes and wait for everyone to calm down.
Lecture rooms are often very cold. Bring a jumper with you, or else you;ll really regret it!!