Polka theatre, LondonThis spellbinding adaptation uses a bulging dramatic toolbox of clever effects and manages to be both epic and intimate Some children’s books – simple stories from familiar worlds – transfer to the stage without much creative heavy lifting. Philip Pullman’s fairytale of volcano scaling, talking elephants and “The Greatest Firework Show in the Galaxy” isn’t one of them. But with buckets of imagination and a sterling cast, Lee Lyford’s new production for six-to-12-year-olds is both epic and spellbindingly intimate. My seven-year-old guest, Artie, isn’t familiar with the book but is immediately enthralled and, at times, so far…