In the UK you are free to basically just change your name if you want. In fact, part of getting it “officially” changed (like for a passport) is proving that you’ve been using the new name in daily life for a while. There’s a restriction about not using the new name for fraudulent purpose", so you can’t pretend to be someone else or whatever, but really what you call yourself and what you want others to call you is your business. I was genuinely surprised that most of the rest of the world thinks it’s acceptable to dictate people’s names to them.