Don't use charcoal inside a tent or modern house. A few people have been killed over the last few years by carbon monoxide from barbecues kept inside a tent even when they thought the charcoal was out. As you say, draughty period properties are probably safe, but be very careful.
Charcoal was used for smelting and working iron and steel too. It wasn't until the 18th century that the use of coke was perfected, and charcoal was used exclusively. We have visited a Wealden furnace, or the remains of it, where ironstone from the surrounding area was smelted. They channelled the water through a series of 'hammer ponds' and cut the wood from the surrounding area. The charcoal was made near the cutting and transported to the furnace. They reckoned that they couldn't transport the charcoal more than about 5 miles over the poor roads in a horse and cart without it falling apart, so all charcoal burning was carried out within that radius. The peak of production at this site was 17th century. The woodland is still there, so in this case, as in many others is 'a wood that pays is a wood that stays'