Lolita and Disney land... No, bad idea. Not only will you have someone's kids following you around, thinking you're some sort of princess (it's cute but...) , but there are so many ways of getting temporarily stuck, having your dress caught on things, and blocking people's way with your massive frilly puffiness.
Also, the staff might have a problem with your wardrobe - though this might be a very slim chance, as none of the staff would know what Lolita Fashion is, or even wear it - but you might be asked to leave because they would think you're a Disney princess or something.
But this is all just me, really. I never looked up Disney meet-ups or trips on EGL (urrg... too lazy... too much effort... lol) but I guess I'm also just being paranoid.
Fantasy isn't always a good thing. See: Paranoia.