If you are coming off the M6 onto the A66 west to Keswick, don't forget a quick right turn to Mayburgh Henge, http://www.themodernantiquarian.com/site/327 and the King Arthur's thing next door to it. Long Meg and Little Meg aren't far away either ;)

This place is quite good too ... and not far off your route http://www.themodernantiquarian.com/site/71

The possible cairn at Elterwater is on the way to Copt Howe you could take a drive past, http://www.themodernantiquarian.com/site/7475

sorry I haven't been arsed to work out the pretty linking thing yet ;)

When are you planning your trip Nige?