Take a look at Stephen Robinson's web site for Her Master's Walks books at
http://www.hm-walks.co.uk/home_nf.htm. Several walks are available as downloadable .pdfs. Walk 1 - Melbecks Moor and Surrender Bridge, a 9 mile circular walk, begins in Gunnerside and takes in various lead mine workings en route. Walk 8 - A circuit of Kisdon Island starts in Keld and passes through Angram and Thwaite.
Stephen's two Swaledale guides (Swaledale and Swaledale, a second glance) contain 10 walks each, cost £4.50p per book, and can be ordered direct from the author. The walks are clearly described with excellent colour maps. The first book includes an 11 mile walk from Keld up to Tan Hill with a return through Ravenseat.
Good luck,
Michael