User blog comment:Merlin-HarryPotter1/Series 5 - Where does Morgana Live?/@comment-5674726-20121104232342

I'd say that Morgana is avoiding any former dwelling of hers that Arthur & Co. or Emrys know about, to guard against any sneak attacks on their part. That rules out Morgause's castle, the fortress and her hut.

I'd say that she's probably got a base of some kind, especially given that she has Aithusa to look after, but it's unlikely that it's one she used before.