Generally speaking from the brown box on the exterior wall they would run cables either internally or externally, depending on how easy it is to get to where they're trying to get to. I expect if you can provide them with a suitable run they could follow it, as long as they don't need to take up floor boards, go through loads of walls, etc. I think if you have an easy run prepared then they would probably accommodate this (with tea and biscuits to encourage it).
Thanks. That's what I was hoping, particularly for the one to get to the back of the house. Do they do a site survey first to agree it all or is it all just agreed on the day of the install? They won't have to lift any floor boards but I would want them to follow behind drainpipe and guttering