I use both a laptop and a tablet for uni. The tablet is good for studying (watching lectures, annotating slides, checking the lms and what not) but there are times where a computer is definitely handy. eg if you have to write a report, it's always nicer to do it on a computer than on a tablet. Also there may be specific software you need for assignments (like matlab or pymol) where you really do need a computer.
Realistically though, I probably use my tablet 80% of the time. And for the times you do need a computer, it usually isn't too much of a hassle to hop onto a library computer.
if you're planning on annotating slides, I find it much more comfortable to annotate slides on a tablet rather than a computer. though that's probably because I used to print my slides and write directly on them. For note taking, goodnotes is my favourite app. You'll need a nice stylus. I use a jot touch, but would definitely reccomend the jot pro (I lost my old one :C )
Note that if you want to stream your lectures and take notes at the same time, it's not really possible with just an iPad. (I tend to carry two iPads so I can watch lectures on one and take notes on the other, but this is probably completely overkill. Together, they still weigh less than most laptops though)