How do I change my name in hospital systems?

I was told to call the hospital, explain things, prepare to be asked for my deed poll etc, and contact PALS if I needed to.

Do I just... call any hospital? I don't quite understand. I thought they'd automatically change but my GP said they're on different systems, so I'd need to do this so I can access blood tests and such.

All I want is my name, my title, and my gender 😭