In the run up to and during their recent exhibition, Medieval Women: In Their Own Words, the British Library digitised and catalogued a number of manuscripts associated with medieval women – and made them available for free online!
This list has since been updated as of February 2025: https://blogs.bl.uk/digitisedmanuscripts/2025/02/medieval-women-manuscripts-now-online.html
The full collection can be viewed here: https://www.bl.uk/research/digitised-manuscripts/
There are some incredible manuscripts to explore, including Empress Matilda’s foundation charter for Bordesley Abbey (British Library, Additional Charter 75724) with her original seal!