Be honest, do you really think you'd be given ALL the oil and gas money for the north sea? National waters extend a few miles offshore, beyond that its fair game (well it would be if nations hadnt agreed already who got what area). Seeing as those treaties were written up as great britain/uk/whatever, the English would have as much claim to (whats left of) the oil and gas as you.
And how many government departments are run from south of the border? You'd need your own:
DWP
DVLA
NHS
DEFRA
Army/Navy/Airforce
Or is it just too convenient to forget to account for all that in your sums? I mean, its not like the army employs any Scottish people is it, would Mr Salmond make them all unemployed, or expect the english taxpayer to pay for a Scottish army?