Cables usually break at the gearbox end because that's where you get maximum load.
Typical fixing is either by knurled aluminium nut, or a single bolt holding a Y shaped bracket. So either way you should be able to undo it by feel, once you've found exactly where it is - usually towards the tailshaft. Once disconnected, if the inner has snapped, the only problem is extracting what's left inside. Usually there's just enough sticking out to get hold and pull with fingers, or pliers.
You may have to lift the cover, so you may have to take the seats out, but I would try from underneath first.
