Britain was far from where people began 4 million years ago in Africa and so was settled only about three quarters of a million years ago.
Even then, the numbers of people were tiny, just a thousand or so. They were our distant ancestors, called Upright Man.
Then came the ice and people were pushed south. After the ice melted a new group of people Neandertals arrived, but another icy spell pushed them away, too. Finally our own ancestors arrived just about 10,000 years ago.