I was told by my Openreach surveyor that they won't allow ducting straight into the house in case dangerous gases enter from the street through it.
With everything moving from copper to fibre there needs to be a box where they house the splice from external fibre to an internal fibre which is usually put outside for ease of access.
In my case the duct from the street comes up into the detached garage and then back underground and up into the house which was enough to satisfy Openreach