The UAS style guide, and the templates built in Mosaic, are intended to ensure that a number of accessibility requirements are met from the start. If you adhere to the principles in the style guide then you will meet the majority of the important criteria for accessibility.
PDF files
Please note that accessibility also relates to your pdf files as well as to your webpage content. PDFs published before 23rd September 2018 do not need to be compliant at this stage, however any newer PDFs must be accessible, and when any older PDFs are updated they must meet these requirements.