My host actually was Julie's roommate, Géraldine. She welcomed me at their home, gave me the keys and answered all questions I got during my stay in London.
The place is a really nice one to stay in London. There, I spend four nights with my brother. Due to the very cheap price and the comfortable bed, I would definitely stay again!
The only thing to complain about was, that it can be quite loud there because the place is located at a big street. But that's nothing Julie or Géraldine are responsible for.