Besides these, I recall a couple more, one on the east coast I think, another on the southern coast. Couldn’t find ‘em because I can’t quite remember them.
Time Team Special 51 (2013) - Britain’s Stone Age Tsunami
https://www.youtube.com/watch?v=3EPNZWBk7i8
Time Team Special 26 (2007) - Britain’s Drowned World
https://www.youtube.com/watch?v=4P9wQj6qX2I
Time Team - Season 19, Episode 3 - The Drowned Town (Dunwich, Suffolk)
https://www.youtube.com/watch?v=Uvg1vm5KqVk
Time Team Special 3 (1999) - The Mystery of Seahenge (Holme-next-the-Sea, Norfolk)
https://www.youtube.com/watch?v=JU37d8kUebk
It hasn’t been that long (30 years???) that the archaeologists put that together with regard to the rising ocean levels, and have shifted their search to offshore.
Or perhaps they figured it out awhile ago, but now have cheaper ways of exploring the ocean floors.