In U.K. schools the term 'cave dwellers' often arises. The question is where were all these caves?

The caves that were used for human habitation were largely in the South, from Kent through to Somerset and into Wales. As most of the country became uninhabitable in the Ice Age these sites tend to be the only ones with significant finds, but the expectation is that humans also lived in forests and other habitats.

I went to a UK school. The term never came up once.

No it dosnt, you are exaggerating.
UK.

In their troglodyte minds.