you are interesting. you like the same stuff, therefore to him, you are probably very interesting.or will be when you talk to him. and if years of watching jeremy kyle has taught me anything, anyone can get laid/have a relationship. and tbh, the other girls' looks are only about perception. they look hot to you because they talk to him and you are worried he wants one of them. to him or anyone else, they may look as ugly as sin. hang out at one of his haunts; try the SU because you could be there anyway and you won't look like a stalker. if you see him on his own, even for a second, go and talk to him. just say hi and that you see him around a lot. ask if you can sit with him or chat. most guys will say thats fine. ask him what he's studying and things he likes. but dont orchestrate it that you only discuss things you have in common - then it looks like you've researched him/a bit creepy. even though everyone does it.
hang by the bar (if your in the pub) then even when he is with friends, you can talk to him when he leaves them to get another drink - alcohol is also a great social lubricant because people feel less inhibited to talk.
don't forget; if he has seen you around and you smile at each other he is probably curious too.
if this is difficult, see if you have any mutual friends and talk to them or hang with them - you might get introduced. then it is easier to approach him when he is with other people because he already knows you