Sky probably placed the order to Openreach for an MPF provide (fully unbundled) which would automatically cancel any existing WLR + broadband (no matter if it was ADSL/FTTC or FTTP) order.
So makes sense for the order to have vanished, if the vanishing is not just another BT Retail problem.
I suspect the simplest route originally would have been to
1. Move out cancelling existing services
2. Move in and order a basic phone and ADSL based service to get things up and running ASAP
3. Dealt with the FTTP subsequent to this
You've confused people here a bit, so maybe similar to the sales people who tend not to take much confusing, particularly for the more rare stuff.
I very much doubt there is a process for handling house moves with regards to FTTP.