This is fiction about the period, but it's fun to read and gives you an understanding of how diverse of a culture existed in the area during that time. The first is a novel called Hild by Nicola Griffith. It's set in the 7th century, before England has been unified and you see the way various cultures are working and competing with each other, the signifiers that different languages hold, and the encroachment of Christianity and it's adaptation with local religions.

The other fun would be the Saxon Chronicles. The TV show The Last Kingdom is based on them. But it shows how the "viking" incursion of England was more of a mix of invasion, trade war, political compromise, and cultural melding.

These are obviously works of fiction that prioritize narrative over hard facts, but both authors did a lot of research and I think in this instance it's helpful to get this kind of exposure to the culture b/c it's so alien from our current conception of England. Almost no one would describe modern England first and foremost as a cultural and linguistic melting pot without an established culture. And although it's not quite true that England didn't have an established culture in the 7th century, things were a lot more in flux. These books help you understand that, and which cultures where struggling to find accommodation within what would become the idea of England in a national sense.