Dover

Dover needs 1 day: the White Cliffs of Dover, the iconic chalk formation that's often the first sight of Britain for those arriving by boat from France, and Dover Castle, with its secret tunnels used as a command center during the 1940 Dunkirk evacuation, are the main reason to visit. April-October is best. It's mid-priced by British standards. It's the point of England closest to mainland Europe, just 34 km from France, and that's why it was key to British defense during both world wars.