Yes, Elizabeth II is a veritable tyrant.
Really, the Scots are fools if they vote for independence. They have the best of all possible worlds as part of the UK.
They live under the UK's [relatively] strong foreign defense and benefit immensely from the billions that the London money-machine feeds to them every year.
And, all the while, they are free to celebrate their heritage and try to restore their ancient language. They are not oppressed by any definition of the word.
Your last sentence hits the nail on the head, ancient Scotland was a mix of peoples and languages, Gaelic as THE Scots language and the Gael culture as the only culture is revisionist nonsense.
I am an Ayrshireman, so the Britons/Brythonic people were my ancestors mainly. I have some Gael ancestry via my mother. But the Gael culture and language does not define me completely.