Visitors to The National Archives have the unique opportunity to explore a vast collection of non-classified government documents. With a free reader's card, anyone can read and even photograph these records. This card is essential for those wishing to delve deeper into the nation's history through its preserved documents.
In addition to the document archives, there's a small museum open to the public. Unlike the archives, no reader's card is needed to visit the museum. Here, guests can discover exhibits that showcase significant historical pieces and stories without any additional requirements.
Source - https://en.wikipedia.org/wiki/The_National_Archives_(United_Kingdom)