Hi Andy,
Did they come and do the cable work prior to install date? I'm in similar boat to you after reading your post and another post you did a few weeks after this one regarding engineer visit. My install date is next week and no one as yet has come and did any work outside the house we do have the black box thing outside our house I wondered if that's the work that needs to be done. Just wanted to check what happened with you in the end so I'm prepared!
[MOD EDIT: Subject title changed for clarity]