Thermair ceiling heater pull cord plastic broken

I have a very old Thermair ceiling heater/light. The ceiling pull cord plastic has sheared off leaving the heater on. I unscrewed the metal casing (after turning leccy off!) to see if I could get the switch off from inside, but it was too far inside the black plastic casing and unreachable. Also, one of the wires to the heater had become unattached, presumably it came off as I opened it up. And both heater wires were in bad condition. Another yellow wire, presumably the earth (?), was still attached. I needed the light, but didn't want to close up the metal casing in case the unattached wire hit metal and shorted out/caused a fire. So I left it hanging down and screwed the light bulb back in, without the shade. I turned the leccy back on and the light works, and the partially unattached heater is, unsurprisingly, no longer on. Is it safe to leave it like this until I can get it fixed properly? Will I be able to get a new switch socket for such an old heater? Would it be easy to fit a new switch socket/rewire it myself, or should I get an electrician? Or would it be better to just get a new heater/light (I'd rather fix it if possible)? I'd be really grateful for some advice. Many thanks in advance.