I don't really think there needs to be a detailed house tour if you going to be watching it for a 3rd of the year and I think you need something to make it more of an event, perhaps a special guest/guests, talking with the families/friends (If they manage to make it) and some VT's into bad auditions and an insight to the world of Big Brother UK/Big Brother world wide. Something the BB8 launch lacked badly.
Your basic structure is quite good though