Whiteford Lighthouse is located off the coast at Whiteford Point near Whiteford Sands, on the Gower peninsula, south Wales. It is the only remaining cast iron lighthouse surrounded by the sea in the United Kingdom. It was built in The tower is
Link to a Daily Telegraph article listing their 20 Best British Beaches. Not all of those on the list are dog friendly, but many (including Wells/Holkham, Norfolk pictured above) are. Will do further research into the matter.