The Cheviot itself can be reached a number of ways, the most interesting being either the Bizzel or the Hen Hole via College Valley. For both of these (if you're taking a car) you will need a permit, and you can get these from Sale & Partners in Wooler (01668 281611). The other side (Harthope Valley) has a good route that links Hedgehope with Cheviot in a horseshoe route. In the same valley, the Schill is good (watch out for adders on a sunny day) and there's a good walk to a waterfall called Davisons Linn. Windy Gyle near Alwinton is a nice walk (and even better MTB ride) but is a little more tricky to find (and is in a military zone). The Cheviots other mountains, Cushat Law and Bloodybush Edge are less popular, although you could link them with a look at Linhope Spout, a very impressive waterfall. As for campsites, Wooler is a very good base and has various take aways and pubs and (I think) two campsites. Alwinton is the other main base in the Cheviots, but if you want to stay a bit further out and travel in, Rothbury is very nice and has various low level walks around the Coquet and Simonside Hills in the event of bad weather in the Cheviots (which as you might imagine, isn't uncommon). A good website to have a look at as a start is www.northumberland-national-park.org.uk. There is also a good book called "Walking The Cheviots: Classic Circular Routes" by Edward Baker. Hope this helps.