Martin,
Dartmoor: Wistman's Wood, Haytor Quarries, Fingle Bridge, Drewsteignton and don't miss the Warren Inn for a pint and a bite! Cornwall: Bill has given you some good locations but I would include South Wheel Frances (minining buildings) and Kynance Cove in particular on the Lizard. But more or less anywhere around the Cornish coast will be productive. If you want a meet up while you are in west Cornwall - let me know.

Neil.