DDA Compliant

Can someone please help me ASAP?

Have been tasked with creating a campaign website for a group of disabled people.
Wordpress immediately sprung to mind due to it’s flexibility.

In the UK, by law all websites should be DDA compliant (Disability Discrimination Act).

Does anyone know of a theme/plug in that will allow the front user to adjust the contrast/colour of the page and or increase/decrease the text size?

Also any captcha’s that also offer an audial alternative to the distorted text.

Thanks!