Wimbledon Theatre (
www.newwimbledontheatre.co.uk) is usually quite a good one for little ones - this year they've got Cinderella. But try to get seats as close to the stage as possible, or book seats in the circle, as otherwise they may struggle to see. The Polka Theatre (
www.polkatheatrecom) has Michael Rosen's Pinocchio, but it's recommended for 6 and up.