Does wiring an Annexe to a Virgin Cabinet require access to the main house?

Hi there,

I have recently ordered Virgin Wifi and my installation got delayed for two weeks as they have to wire the annexe to the cabinet. The main house already has virgin but I do not have access to it. When chatting to live chat they mentioned wiring the Annexe straight to the cabinet. So does that mean I won't need to have access to the main house at all? Because I have no way of letting someone into it on the date they're coming. Only access to the annexe I am living in. 

Just want to see if anyone has had this experience already.