You have to notify the police not get approval. They can "impose conditions and restrictions" for safety or to limit the rights of others to travel freely, after which they'll also be somewhat liable to protect you from counter-protesters, or lunatics trying to drive their car at you.
Just about every country requires some kind of advance notice if its not just a few people walking along the pavement/sidewalk and your going to obstruct traffic or block others movement
https://groups.friendsoftheearth.uk/resources/your-rights-an...
Reform's manifesto includes[2]: "Stop the Boats with our 4 Point Plan. Leave the European Convention on Human Rights."
[1] https://fra.europa.eu/en/law-reference/european-convention-h...
[2] Page 5 of https://reformuk.org.uk/wp-content/uploads/2025/10/Reform_UK...