That is more of a legal presumption of ownership to the midway point of the frontage.
The actual position needs to be checked by someone who knows what they are taking about so highly advisable avoid cheap processing conveyancers, get a an experienced property lawyer.
This is quite useful as it gives you some general information which also assists in some useful points for consideration you friend might not have considered.
http://www3.lancashir...5409&pageid=29027&e=e
It needs to be properly checked that there is a sufficient right of way granted in order to get all required access to and from the property (on foot and by vehicle) including rear or any other access required to the land over any land outside that to be purchased.
Any restrictions or obligations need to be checked carefully in the specific wording in any documentation and the circumstances of the individual property and those of your friend.
I imagine that the agents have the contact details of the seller and their solicitors to be able to see if they can pass over any information they have or can get about the private road (I'd say any decent legal advisor acting for a buyer would ask for it!). Unless it's a special property for any reason and they have plenty of potential buyers then you'd think in this market they would try to be helpful.
Beware if a simply answer of we have/we will get an indemnity insurance policy to cover it - she needs to know the position, the cover and any potential implications properly to be able to judge whether this is sufficient. Like any insurance policy, it's not always a failsafe so she needs to know the level of risk.