Those rules are England only
Not uk wide
There will be other specific guidance in the other home nations
To clarify, because of devolution there are separate laws for N. Ireland, Wales, England, and Scotland.
Four sets of laws. However the wording applying to leaving home is identical in each country's laws.
This police guidance is not law or rules, it's just a common sense interpretation/guidance for the police. Identical principles would apply to Wales, Scotland & N Ireland because the laws are the same.
So for all intents & purposes, while this is guidance for the English police, it is likely to have been compiled by people with a reasonable grasp of law, and would apply to each of the four countries.