Simon, have "fun"! You don't have to worry about whether you're going to marry the girl right now or not :-) Ask her out and see what happens. You all may not hit it off (she may want to do mostly clubing which you don't, for example) or you might hit it off well in which case there will be the two of you to think about how to manage a relationship. But right now, like Flinty says, just go get a cup of coffee or something. It doesn't matter if she "likes" someone else at the moment, unless you were part of the conversation you don't know if it's "like" as in the way you like her or more real or whatever. That's what you get to discuss over coffee, whether she's seeing anyone steady, does she want to go out on a "real"/evening date, that you don't have a car/can't drive, does she? etc.