BABY STEPS: Prince George will make his first official visit overseas when he accompanies his parents, the Duke and Duchess of Cambridge, on a tour of Australia and New Zealand in April. According to Kensington Palace, Queen Elizabeth II has approved the trip, allowing the second and third in line to the British throne to travel on the same flight. The prince will be eight months old when he undertakes the tour, which begins on April 7 and runs through April 25. Not that this is his first trip outside England: He has recently returned from a holiday in Mustique with his mother and maternal grandparents.