The National Archives are a non-ministerial department, and the official archive and publisher for the UK Government, and for England and Wales. They are the guardians of over 1,000 years of iconic national documents, and collect and secure the future of the government record, from Shakespeare’s will to tweets from Downing Street, to preserve it for generations to come, making it as accessible and available as possible.
https://www.nationalarchives.gov.uk/
The National Archives has a comprehensive research guide section and can help with many types of research. Popular collections include:
- Military Medals and Service Records
- Wills
- Ship Passenger Lists
- Alien Registrations
- … and many more.
A good starting point would be their Discovery section: https://discovery.nationalarchives.gov.uk/