>"popular idea that the UK was covered in dense forest after the ice age until modern times is mostly erroneous these days"
When I was growing up in Scotland, I'm reasonably sure I was told that 95% of Scotland was once covered by the Caledonian Forest. Certainly that's what I've been telling people since then:-) But according to https://en.wikipedia.org/wiki/Caledonian_Forest it was estimated to have covered 15,000km2, whereas Scotland is 78,000km2, suggesting it was less than 20%.