There's no need to get heated about this. Best just to look at the facts:
The Scottish Parliament and Welsh Assembly do not collect their own exclusive taxes from their citizens, and if they did they would not be able to support themselves unless those taxes were unacceptably high. I don't like the word 'subsidised' but the fact is that England contributes to the running of those countries because this is a United Kingdom.
There is no such thing as 'Scottish oil and gas': it is British. If Scotland ever becomes independent then what part of the North Sea would become Scottish waters would be a matter of international debate and decision. Very likely, the sea boundary would continue the land boundary and go from southwest to northeast, leaving a huge chunk of the North Sea as UK waters, with a northern slice as Scottish.