If I changed my name and transitioned, are you saying I could:
- Get a new birth certificate with my new name and my sex marker changed
- Get a new passport, ditto
- Driving license, ditto
For a driving licence you just need a statutory declaration and as Man Friday found out this can simply amount to you writing on the form 'I identify as a man'.
For a passport you also need a letter from your GP.
To change your birth certificate you need to apply for a gender recognition certificate. For this, you currently need two medical reports, one of which contains a diagnosis of gender dysphoria. You also need evidence that you have been 'living as' your preferred gender for 2 years. The evidence they are looking for is things like driving licences and passports (see above!) as well as less official documents like payslips, gas bills etc. They suggest sending 5-6 docs to cover the whole of the 2 year period. Full details here:
www.gov.uk/apply-gender-recognition-certificate
Once you have a GRC it's unlawful for anyone to reveal your trans status without your permission if they came by that information in a professional capacity.
www.legislation.gov.uk/ukpga/2004/7/section/22
Last year the government ran a public consultation on whether to change the process of getting a gender recognition certificate to remove the requirement for any diagnosis or doctor's reports, or any evidence of living in the preferred gender, and just require a statutory declaration. The consultation received over 100,000 responses and these are still being analysed.