BBC History: In-depth articles, multimedia (like games, virtual tours and animations) as well as bite-size material like timelines and short biographies of historic figures. The site is divided into a broad range of topics from Ancient History to Wars and Conflict. Within each topic you'll find sub-topics devoted to key areas such as Ancient Egypt or World War One. Much of the content is about British History.
Collect Britain: A rich selection of digitized historic content; audio collections
Britannia History: Free access to more than 25,000 directory listings of British history related venues; browse through news, features, competitions and a searchable Timeline of British history from 10,000BC to the present.
British History: A complete timeline of British history with descriptions, graphics, and photographs
History of Parliament: A research project creating a comprehensive account of the parliamentary politics in England, then Britain, from their origins in the thirteenth century.
How Stuff Works: History of the United Kingdom: Introduction to History of United Kingdom, History of Great Britain 1701-1837, History 1837-1914, History 914-39 History, 1939-70
Infoplease: United Kingdom History
School History: British and World History: A collection of resources students and teachers
United Kingdom History: A travel site with great history facts