Graphic presentations are really necessary to appreciate how ancestral migrations occurred over time. This one by the Bradshaw Foundation is one of the best. (But you'll need to be patient while it sets itself up.)
Family Tree DNA tailors the migration pattern of your family, but this is a "members only" feature.
Once you have a sense of how these patterns work, it's time for the next installment on whether we are descendents of a garrisoned Roman soldier and a tribal British woman.