since jacob rees mogg has
decided that change.org petitions aren't valid, only petitions hosted on the official gov petition site are, here's a masterlist of all blm/blm adjacent petitions that i can find.
you do need a uk postal code to sign these petitions, so if you're outside of the uk then you could find one online, although i don't know how much i'd recommend that, since the government's already being finnicky about what petitions are valid, and i don't want to give them a reason to find these petitions invalid.