Above map, 18,000 year ago.
R1a's spend the Last Glacial Maximum(18-23,000 years ago) in the Ukranian Ice Age refuge. The above map shows the direction of migration at about 12,000 years go.
There is much debate presently as to which DNA group, R1a or I1a, are the 'Viking Gene.' In my opinion, it's both.
The Orkneys where the 'jumping-off' point for the Vikings on the way to Iceland.
So did R1b settle Britain?
Looking at that map with all the arrows pointing to the frozen north, I have to wonder....there must have been some really bad mothers chasing after them.