This deed poll is drafted for England and Wales, where the common-law freedom to change your name and the enrolment procedure at the Royal Courts of Justice both apply. If you were born or currently live in Scotland, the position differs : a change of name is usually recorded through National Records of Scotland, which can issue a new Scottish birth certificate rather than relying on a deed poll, and many Scottish residents use that route instead. A deed poll executed in England and Wales is still recognised by UK-wide bodies such as HM Passport Office and the DVLA regardless of where you live, so the document remains useful across the whole of the United Kingdom.
In Northern Ireland, deed polls operate on similar common-law principles, but enrolment where required is handled through the Royal Courts of Justice in Belfast rather than London, so check the local procedure before assuming the England and Wales enrolment route applies. For anyone with a connection to the Isle of Man or the Channel Islands, the deed will generally be accepted by UK government departments, though local registries may have their own preferences.
The practical distinction that matters most is not geographic but institutional. Some banks, building societies and utility providers still insist on an enrolled deed poll even though government departments accept the unenrolled version. If a specific organisation has told you it requires enrolment, you need the fuller court process. For everyone else, the unenrolled deed executed with this template is sufficient, and if you later need certified copies for different institutions, keeping several signed originals is far simpler than requesting them from the central document catalogue after the fact.