Any errors identified in your Siteimprove report should be actioned as soon as possible and thereafter on an ongoing basis as your fortnightly reports come in. The latest Accessibility Regulations have already come into force, therefore all sites need to be compliant with the Web Content Accessibility Guidelines version 2.1 - AA standard.  The latest Accessibility regulations for Public Sector Websites (Part 2 Section 5B) came into force on 22 September 2020.