I'm not sure if anyone has put this information out before but I thought these sites may be helpful to someone.
When I do manage to get out with my husband toilets are often a problem, so two years ago Pete bought a RADAR key( only a couple of pounds off their site, radarshop.org.uk
You often find they are cleaner than the public ones, (which are often shut)
The second site I found through my iPad and I have the app store on this. If anyone has an iPhone or iPad or apple computer they can download the app.
You can also access the site if you put spinal.co.uk/news/guide for accessible-toilets.uk. This will tell you where a toilet for disabled people can be found, needed on a day out. The web I think for a pc is wheelmate.com/en.
Hope some of these are helpful, Especially the radar key.