Ice ages probably made earlier colonization prohibitive if not impossible.
Beware the Luddites. They’re thick around here.
The glaciation came and went, and came back, and went again, etc, but that probably means the deposits are both deep and moved around. Plus, “Doggerland” has produced human fossils as well as stone tools (now the floor of the North Sea), and when sealevel was lower, people lived down there.
Good advice too, btw.