There is a new play of this story(synopsis ) which is on all over the place at the moment - for ages 4 and up (or even 3 at a pinch) - it sounds absolutely brilliant for kids, esp the ones who like to say "poo-head" a lot!
I haven't been able to find a list of venues, but the production company is called Kipper TIE and if you google them and the title you should find one near you.