From my research when coming from a pole above they need to first bring it down to ground level because the connection in the box on the outside needs to be spliced/ welded and the equipment involves a built in microscope and is not something that can be done from a ladder.They will install the outside box near ground level. The cable from the pole to the outside box can be very long but the cable from the outside box to the inside box is limited to 10 metres. They are very flexible about where they install the inside box but I have never known them to install it in a loft. They might be willing to do that if your loft is essentially a room with stairs to access and proper flooring but they won't want to climb a loft ladder and balance on ceiling joists.
Have a utube search and you will see.
The box on the outside is about the size of 4 bluray cases stacked on top of each other and the inside box is about half that.