Late Iron Age coins appeared in some, but certainly not all, of the British tribes. Before the Roman occupation of Britain, the people lived in tribes. In the late Iron Age some of these tribes used coins. The coin used in pre-Roman Britain seems to have been concentrated in the southeastern part of the area.
According to the article, Britain’s First Coins by Chris Rudd, published in The Journal of Ancient Numismatics, Volume 1, Issue 4, there were eleven tribes that had coins. They were the Atrebates, Ecuni, Cauti, Ragni, Belgae, Durotriges, Trinovantes, Dobunni, Corioltouvi, Catuvellouni, and East Wiltshire.