The Queen doesn’t have an official surname. Her official title is ‘Elizabeth the Second, by the Grace of God, of the United Kingdom of Great Britain and Northern Ireland, and of her other Realms and Territories Queen, Head of the Commonwealth, Defender of the Faith’. No last name needed.
Queen Elizabeth can choose Britain’s Poet Laureate, who alongside an annual salary also gets paid with a barrel of sherry. In 2019, Simon Armitage was appointed Poet Laureate and he will serve for ten years.