Are you, perhaps, conflating Britain and the United Kingdom of Great Britain and Northern Ireland? There’s a potential upcoming referendum about the latter, not the former.
I made a comment elsewhere saying that people shouldn't get upset about getting called "British" if they consider themselves Scottish above all. But likewise I don't think it's smart or considerate to be all "well actually..." about something deeply personal and strongly felt like someone's national identity or gender or anything like that. That's sort of asking for conflict.