In the UK there is no legal name, you can call yourself whatever you want and for quite a while I did that. And that was how I came out to everyone as Jessica and started my version of full time. Then a month or so after I started HRT. Where possible I changed names or created a new identity.
But a number of documents such as bank details, driving licence, etc could not be changed without a simple declaration, a deed poll. I piece of paper saying that I will be using this new name from now on and the other is dead. With that paper and old ID I could just change everything apart from birth certificate (name and gender) or HMRC (tax man, gender) This I did when I got married. I could then change gender on my driving licence, titles and name at banks, insurances, local tax etc. And change gender at the NHS (doctors etc)
Passports are a little more awkward and I have not changed that yet as it requires proof of gender change from a doctor and I am in the process of doing that.
The last change is quite hard to do. To change name and gender on my birth certificate requires a Gender Recognition Certificate (GRC) to get one you have to provide lots of documents that show you have been using your name for 2 years, and two doctors letters proving that you are undertaking gender re-assignment and if that is not including surgery why or when it will happen. And lastly you if married you have to get divorced or get permission from your spouse for it to continue else you will not get one. Then a panel decides how trans you are. Needless to say very few actually goes through this
So it starts very simple and ends so so complex.
And if you go through all this the government can still insist that you are your so called biological gender that means you would be (as a female) send to a male prison and a male ward in a NHS hospital.
Hugs
Jessica xxx