Whether the incoming line is in ducting or not is likely to depend on the age of the house and whether the line has been replaced in recent years. Not sure when new builds were first supplied via ducts - late 80's maybe? If you line is in duct it should be obvious where it comes out of the ground, either you can see it or there will be a cover over the end of it attached to the wall.
I can see this becoming a major issue for FTTP installs, at the moment, for the trials, it sounds like Openreach are just applying as much resource as required to get it done but I suspect the costs will be enormous if every install is as difficult. It wouldn't surprise me if when FTTP is mainstream the householder will be supplied with the ducting to lay themselves before the rest of the install happens.
It also seems that underground supplies to pre 80's/90's developments are all direct buried under pavements too, so to get FTTP into these I think the effort and mess might be similar to the cable rollout twenty years ago - holes in pavements everywhere for ages!
