Just like every other parent across Britain, Kate Middleton and Prince William are preparing for their youngsters' return to school this September.The Cambridges have enjoyed a fun-filled summer holiday, with trips to the Isles of Scilly and the Queen's Balmoral Estate creating lifelong memories for Prince George, Princess Charlotte and Prince Louis.The Duke and Duchess' youngest son Louis is three years old and started at nursery school this April, while his older siblings Charlotte, six, and