The Painted Garden by Noel Streatfeild
Jane's family is all set to go to America for a long time. Everyone is thrilled -- except Jane. How can Jane leave behind the only creature that loves her -- Chewing-gum, her beloved dog? Jane's father, a writer with terrible writer's block following a bad car accident, is invited to spend a year in America with his family to recover. Jane's brother and sister are hugely excited, but Jane, the awkward middle child, can only think of the bad things about leaving home. Once in America, however, things change rapidly and Jane lands the star part in a Hollywood film! Before long she becomes much too big for her boots and has to learn about coming down to earth the hard way before the story ends happily.