An A-Z listing by University of accessible maths resources.
Another useful website is this accessibility and inclusice design manual from the Department of Education.
These links are regularly checked but if you notice any that are not working or you would like to share your own resources, please do get in touch.
Guidence for conversion from LaTeX to accessible HTML and SCORM with BookML
A very useful guide to Accessible teaching for Maths, Stats and Physics written by Scarlett Spackman and Christian Lawson-Perfect
Christian is also the developer of Chirun which helps make flexible and accessible notes from LaTeX or Markdown source.