Making an unenrolled deed poll
GOV.UK says 16- and 17-year-olds may choose to make their own unenrolled deed poll. Its general instructions require signing in the old and new names with witnesses. Use a provider or the GOV.UK guidance, and check that the intended recipient accepts an unenrolled deed. Some organisations may ask for an enrolled deed poll. GOV.UK: changing a child’s name; GOV.UK: changing your name by deed poll
The deed changes the name record; it does not by itself amend a passport, bank account, school record or immigration account. A young person should understand the permanent practical consequences and keep the signed evidence safe.