What is this self depreciating mindset you have of yourself? And thinking "Oh she's too good for me" is stupid. Improve yourself so you get to the point where you're more or less equal to her. Just go up there and tell her about your stutter. Its the first thing you should do after a friendly greeting. If she's worth your time then she won't give a fuck about it. Don't hide it because otherwise it'll be awkward all night.