You could also pop along to the next meeting of your local TRF group. Although they (from my limited experience) tend to be a bit more hardcore than the type of trail you are looking for.
sorry about the 1160 I could not resist,And you being an IT man.As for the question,as Spout said keep a look out on the site.Or get the os map out and make one up and have a look and a play.If its mud you want try the road to Sunderland point very muddy last weekend I almost got caught out with the tide!!
GRAHAM