We did this in July.
You get a voucher for a storytime in MK. It's held right next to Tony's, to the right of the entrance. You have to make reservations ahead of time, and they only do it a couple of days a week, so plan well.
Anyway, when we went, the Fairy Godmother came out, read a story, signed autographs, and posed for pictures. It's really a nice, relaxing thing to do if you have young kids. The little ones get to sit in the front while grown ups sit in the seats in the very small theatre. The character who visits varies, though, so you can't count on any single person showing up. I'd say only about 20 or 30 people there when we went, so it's a very quiet experience.