Presumably all the people in the public eye have been allowed some degree of hairdressing as part of their work all along? No grey roots for Sophie or wild hair for Harry, even before today's lifting of restrictions, and similar for some presenters or politicians (though, famously, not others like Boris, though I'm sure he could have if he wanted).
Haven't heard anything from my salon that says they aren't doing highlights or colour, nor anything about patch tests, so hopefully they've decided 4 months is still OK.