Do accessibility review and add accessibility statement

[vickytnz]

We need to run accessibility checks on the site and create an accessibility statement similar to https://prototype-kit.service.gov.uk/docs/accessibility

[anandamaryon1]

Agreed. Gov's was an internal test, so I think that'd suffice, if anyone here is able to do that?

[anandamaryon1]

We'll be performing an internal review in January, with help from @mcheung-nhs. Following this, we'll write and publish the accessibility statement.