Why not get the children to choose one of these adverts, and write a story based on the description of the story in the advert.
Also try to add a little humour where possible, ensuring that the children are aware that it's not real - you're just pretending! "Paul"), making sure that this is not the name of someone in the class.
Before the lesson, put a chair in an empty space in the classroom.
They don't need to have read the book which is being advertised, and you can get them to compare their own story to the real version when they have finished.
Take 4 or 5 unrelated but interesting objects and challenge children to create either a skit or a character description of the owner.