By Joseph Wilkes & Sarah Tulloch Kate Middleton will be feeling “vulnerable” as her husband Prince William leaves her side to return to Royal engagements for the first time after she revealed her cancer diagnosis to the world, a royal expert has said. Today, the Prince of Wales resumed his Royal responsibilities with a measured approach, according to a palace insider, as the 41 year old visited Surplus to Supper, a charity in Surrey that redistributes surplus food. He pitched in at the kitchen and assisted with loading prepared meals into delivery vehicles before making his way to a youth cent…