There are two types of installations, a one stage and a two stage.
With a one stage installation everything is done on that day, both interior and exterior work.
With a two stage installation, the interior and exterior works are performed on separate days. The final act would be to perform a fusion slice of the interior and exterior fibres, which would then be stowed in a customer splice point (CSP). There are both interior and exterior CSPs available.
Knowing that you currently have the metallic pathway entering your home through a duct and would like the fibre to take the same route, I imagine that an "outside in", one step installation will be performed. I presume that if you were to go out to the lane and look in the joint chamber, you would see a connectorised block terminal. (As an example, see the
images here.) The connectorised fibre would be run from the joint chamber back into your house where a "field fit" SC/APC connector would be added at that end, to plug into the ONT.
Once completed, it would be interesting to know the make and model of the ONT so fitted.