Short answers, pulled from the story.
The Kingdom of Great Britain was created on the 1st of May 1707, when the Acts of Union came into force, merging the Kingdom of England (including Wales) and the Kingdom of Scotland into a single state. The union was based on a Treaty of Union agreed in 1706 following negotiations between representatives of both parliaments.
Queen Anne was the first monarch of the Kingdom of Great Britain, reigning from 1707 until her death in 1714. She was the last Stuart monarch and had previously been Queen of England, Queen of Scots, and Queen of Ireland since 1702.
Robert Walpole (1676-1745) served as First Lord of the Treasury from 1721 to 1742 and is regarded as Britain's first prime minister, with the term in use by 1727. He stabilised the Hanoverian government after the South Sea Bubble collapse, reduced the national debt and land taxes, and maintained peace through diplomatic means for most of his tenure.
The South Sea Bubble was a financial collapse in 1720 in which South Sea Company stock rose to £1,060 on the 25th of June before falling to £150 by the end of September. The crash implicated Cabinet ministers including the Chancellor of the Exchequer and the Postmaster General in fraud, and threatened the stability of the Hanoverian government until Robert Walpole intervened to restore confidence.
The Seven Years' War (1756-1763) left Great Britain as the world's dominant colonial power. During the miracle year of 1759, British forces captured Quebec City, Fort Ticonderoga, and the island of Guadeloupe, while defeating the French navy at the Battle of Lagos and the Battle of Quiberon Bay. The Treaty of Paris of 1763 transferred New France and severely restricted French military presence in India.
The Kingdom of Great Britain ended on the 1st of January 1801, when the Acts of Union 1800 merged it with the Kingdom of Ireland to form the United Kingdom of Great Britain and Ireland. The union was driven by Prime Minister William Pitt the Younger following the Irish Rebellion of 1798, which was suppressed with a death toll estimated at between 10,000 and 30,000.