Various screen readers are available.
Hear an audio version of this website by clicking on http://www.screenreader.net to download a free screen reader for Microsoft Windows called Thunder. The site it takes you to asks for a donation, but you do not have to make a donation if you don’t want to.
Macs now have screen readers built into them.
Trafford Disability Information Service plans to produce a factsheet about making information accessible later this year, which will have more information on screen readers in it.