>>2055859 (OP)
Witches' magic flight would predate any kind of mechanical powered flight, and thus regulations regarding it. So, they would likely get grandfathered into the system, with some reasonable restrictions to prevent stupid witches from killing themselves (e.g. don't fly into controlled airspace if you don't want to add to the bird strike statistic), but otherwise largely freeform, like bicycles. Take off and land whereever as long as it's not trespassing, ride whatever broom you want, baisically just be reasonable and don't get in the way of bigger and more dangerous aircraft.
Aside from rules written in blood, free flight also comes with some privacy concerns, so that might also introduce some rules. There likely will be some restrictions on aerial photography to prevent spying witches, you'll have to get permission to carry a camera. Old dense city centres would have witch leylines at regulated height over the street, to prevent them from peeping into the windows and disturbing foot traffic (they can briefly deviate from the leyline to land or to rise over the buildings into unregluated airspace, but no flying into the windows, even if it's your window).