trust me, you will not have opportunities like this once you're out of school.
i remember first few times when hot chicks would talk to me. i was so shy and uncomfortable, thinking they were way out of my league, that i blew some golden chances. but towards middle to end of my college years, i got comfortable talking to hot girls and i got a lot of play. i even heard from their friends that these hot chicks thought "I" was out of their league. :Q
go for it. worst that can happen is being turned down by her, but learning to polish your skills towards next hot chick.