Great Britain was settled each time, and occupied for thousands of years, but the occupation may have ended with the next glaciation. Trouble with really thick glacier cover that goes on for hundreds of miles is, nothing much to eat, and no fuel for fires. Even the sudden formation of the English Channel didn't slow down prehistoric humans.
Also, I'm not on board any gradualist onset models.
It's interesting that "fossil" CO2 levels found in deep ice cores show that the CO2 levels rose 100s or 1000s of years *after* the world warmed back up.
The ice core data also support that the onset of an ice age is rapid. I'm glad I won't live to have to cope with it.
Food production will rapidly decline. Glaciers don't come as far south as Colorado (mountain glaciers excepted) but this land will be useless. Weld County, Colorado, is one of the most productive agricultural counties in America. Next ice age, it will be tundra. Great Plains agriculture will be lost. Populations will flee south and there will be great wars over the reduced livable land.
If only the warmist fantasy was true.