Share your plan with your parents. Tell them about the characters and about your plot. How are you going to make sure that you are meeting the criteria for a Punch and Judy Show?
Make a puppet theatre in the garden or at home. This need not be very fancy: you could hang two towels on the washing line and tie them back to look like theatre curtains, place a table between them with a throw over the top to hide you and ... Bob's your uncle! Now get an ice-cream for the whole family and sit them down. Your job is to interest them in your forthcoming show. This might be by saying something like: Roll up, roll up! Don't miss the Punch and Judy show of the year next Saturday at 3.30 in the afternoon. I can promise you all the usual fun and frolics and there might even be an unexpected character to surprise and delight you.