I like this site. It does exactly as it says on the tin. Walks with wheelchairs is a site where you can     

* Read reviews of the routes before trying any walks

* Download walk directions and detailed OS maps free of charge

* Share your own routes for walking with wheelchairs

* Add your own comments for others users to view

Designed by a Cathy Nettley a nurse in Somerset, there are over 500 different walks and this is being updated daily.

You can, as you might expect, refine your search for a walk with a wheelchair by region and distance, but you can also choose by gradient and terrain.

http://www.walkswithwheelchairs.com/