Ancient Britons tended to build round dwellings with mud rendering around wicker frames in the south. Further north, Britons would use stone instead, though still in round wall design. The thatched coned roof was also common. They did not use chimneys and would have a fire burning in the middle of the dwelling. The smoke would rise up inside the thatched and cone shaped roof to slowly seep through the straw and out into the open. This stopped birds and insects nesting in the thatch. Sometimes these dwellings were clustered within great hill fort Palisades and had done so for many hundreds, if not thousands of years. The Great Hill Forts were like market towns where people would come to trade farm produce and other manufactured items, like tools. The people were illiterate before the time of the Romans and would have spoken Celtic dialects like that of the Welsh, Cornish or even Bretons of North West France. They had a religious culture based on Druidism, which today is thought of in romantic and mystical ways, though it is possible they did practise human sacrifice on occasions. This adds a more sinister aspect to the druid priests.
In Gaul, today's France, young apprentices were sent to Britain to be schooled in the ways of druids. It must have been done through word of mouth and been a very hands on method of tuition if they were illiterate and they may have had some form of rune carving that meant certain things. This religion was all but vanquished after the first couple of hundred years of Roman rule, and when Christianity came it would have diminished further.
Many of the communities throughout Britain lived in such abodes seen above until the Romans began to build villas and great cities.