Mates, you're an ancient people. Your roots on the British islands go back 7,000 years. The sequencing of ancient DNA has revolutionized our understanding of this stuff.
https://en.wikipedia.org/wiki/Geneti..._British_Isles
You can learn a lot by sending a vial of saliva to the one of the DNA analysis services. If you're a native Brit, your patrilineage probably goes back to an Indo-European speaking nomadic chieftain who collected skulls and concubines on the Pontic Steppe 5,000 years ago. His descendants arrived in Britain more than 4,000 years ago. Your matrilineage might go back to the dark-skinned, blue-eyed hunter-gathers like Cheddar Man who were in Europe for 30,000 years and rubbed elbows with Neanderthals. Or it might go back the farming people who migrated out of Anatolia and pushed into Britain via the Iberian Peninsula 5,000-6,000 years ago, the makers of Stonehenge.
Celt, Saxon, Dane, Norman--they are all minor variations on the northwest European type.