I need to travel from Southfields to Elstree daily for a few weeks.
The last time I did this journey, a few years ago, I used to take the
District Line to Blackfriars and change onto the Luton line. I know
Blackfriars tube is closed, and the journey planner tells me to go via
Kings Cross, but having heard bad stories of KC interchange isn't
changing at Blackfriars using Temple or Mansion House still the
easiest option? Any other suggestions?

Paul