Snafu, I suggest you have a look at the accompanying map of the North Sea and North Atlantic. Click:
http://www.bbc.co.uk/news/uk-scotland-scotland-politics-20042070
and scroll down to the map.
It shows the sea areas that would "belong" to Scotland and England separately. As regards the Northern Isles, just look at the map and note how relatively little of the blue sea-area would belong to them, even in the unlikely event of their becoming independent. I'd offer the Channel Isles the same odds!
I don't know if you're aware of it, but the part that would be Scotland’s in the North Atlantic is the very area where oil-finds are beginning to be made. England has no coast abutting this sea area so would have no claim whatsoever on it. Even still having Northern Ireland (NI) would be no help, because the Irish Republic actually stretches further north than NI does!
England, not Scotland, is the country which will have zero access to
that oil if the Scots vote for independence. Plus, of course, England’s part of the Southern North Sea is the area that is already dying on its feet.