It depends on how much you want to spend and how long you intend to keep the car.
For a full repair that includes cutting out the rust and replaceing the panels, you are probably looking about £500 at a body shop. I’ve been out of the car repair business for a while so that’s just a guesstimate, but the panels are about £25 each, labour of fitting, paint etc so few hours labour and materials.
Picture 6 looks like the sill will go into a hole at some point soon so another method is just to patch it and paint it over, probably looking about £100 if they rub down the wheel arch as well.
I may be out with my prices so anyone else do correct me, but that rust looks like most of it is coming from the inside out so the only proper way to get shut of it is to replace the metal.