Sharing a bag of sweets with Heston Blumenthal is like tucking into a packet of jelly beans with my five-year-old. Sarah Rainey tries out Heston Blumenthal's new, limited-edition Topsy Turvy menu at his Fat Duck restaurant in Bray, Berkshire Sarah looks at the menu with the wonky, vision-impairing goggles. Diners - paying up to £325 each - can enjoy the …