Or just explore lead, copper, gold, iron, graphite and numerous rock quarries or mines. Other minerals too. All in Cumbria and the Pennines within a days travelling.
Although I have seen a little of the Cornish industry as well as Pembrokeshire, Snowdonia, peak district and Scottish mining areas in the past. Think the area of Scotland heading up the A74/motorway has a few interesting mining, historical features worthy of a visit.
Back on something slightly related...it would be gd if the NT made more of any mining or other industrial heritage on their land. I mean they're a big Lakeland landowner and in the heritage sector too.