You're right, AlmostAlwyn. MI5, MI6, Scotland Yard, Whitehall, diplomats, consulates, ambassadors, a foreign office, MoD - all UK institutions, agencies and services, not English - Scotland pays for these pro rata on an equal level with England, N Ireland and Wales. We are not given the use of them for free. When you think about it like this, we are already paying a lot of the costs of running a country now, whether the costs of running devolved services or contributions to Westminster responsibilities.
Also currently these are all based in London and therefore to access employment in any of them requires living in London. Independence would provide a raft of highly paid quality employment, the tax revenue paid by these staff would benefit the Scottish economy, and the brightest and best in our society would no longer need to leave Scotland in order to fulfil their potential.
People rarely mention the economic benefits to Scotland going independent - our share in all of the UK assets which would need to be negotiated and agreed. The fact that Scotland would no longer have to subsidise the rest of the UK's excesses, like HS2, Trident, new airport runways in the South of England, etc.
As for the oil. Geographically Scotland has the vast majority. And that is how these things are traditionally divided. There would be discussion on where to draw the line but still Scotland would have the vast majority.