It's really interesting stuff - the dna profile of the British (and the shape of their faces) does change in line with recieved wisdom about "celtc" areas and "saxon/viking" parts, but we all have loads of stuff in common in our dna that pre -dates the "bronze age".
I really love this stuff - me and Mrs Wiggy have done a fair bit of family history research, and yr right, there was more movement around the country than people tend to think.