I suppose the great unsayable about Union politics is that despite the barracking you see in the Commons, there is rarely any real antagonism behind it. In practice, there is a lot of collaboration that you don’t see between the parties. They have to have reasonable relationships.
So it’s not Tory v Labour or variations thereof.
I know the SNP no longer work like this at all (they did when Salmond was in charge to advance devo powers).
Strategically this why the SNP are just nowhere in the Commons and it is probably why they have got themselves into a mindset that they must control matters in the Scottish Government.
It’s not actually how politics has generally operated in across the U.K., but the different approach now taken by Sturgeon has led to an effective “gun to the head” situation where independence is said to be with them only. It is not a sophisticated approach at all