I'm a person, then English, then UK-ish. Which is part of the issue - 'UK-ish' is a clumsy term. I'll say I'm from the UK. But in my head, the first nationality that comes to mind is "English".
I'm aware that many people are irrationally prejudiced against "the English" and don't even bother trying to hide it because it's a fashionable irrational prejudice. Those people can shove it up their arse. I'm not a fan of irrational prejudice, fashionable or not.
Strictly speaking I'm also Eurasian, but that's far too large an area to be relevant as a nationality.
I'm Nigerian then.
All my grandparents are 100% Irish but I've lived in England since I was about one month old.
I call myself English.
Because you are. Nationality is a state of mind thing. I'm one of the first generation of my family born in England. It's very likely that some of my ancestors fought against England. But I'm not them. I'm me. And I'm English. My heritage is that of Shakespeare and Chaucer and Dickens and William the ******* and all the rest of it. The fact that none of my ancestors (as far as I know) were in England in those days is irrelevant. They're not me.
Come to think of it, it's also very likely that some of the ancestors of most English people fought against England. Just a bit further back in time.