Large sections of the English Cheviots are within the Northumberland National Park
Parts of the Park include the Otterburn ranges. Information on firing times is here
Shepherds Walks offers a variety of walks and services in the Cheviots
More information on the Cheviots and the surrounding area is at sites like this one
The Megalithic web site will tell you about some of the archaeology.
Finally, you will find even more about the archaeology along the Border Roads in these two books produced by Coquetdale Community Archaeology – The Old Tracks through the Cheviots and Walking the Old Tracks of the Cheviots. They are available from any good bookshop, or online here and here; they can also be obtained from the publisher