Boo for BT! They have totally failed to deliver the WiFi router.
So I popped over to the old house, picked up the modem/router/WiFi access point from there, brought it back over here, plugged it in, faffed with it, plugged it into a different socket, and Ta-Da! We can has broadband!
I think my heart grew three sizes :->
Now to wrap presents, have a bath and then exchange Christmas presents with la famille.