I love the "should'nt cost a fortune" bit!!!!
First registration of a property in the Land Registry - which this will be- can take years, be disputed, be refused for all kinds of reasons. Most messes can be sorted out but the bigger the mess, the greater the trouble, inconvenience and cost.
G has already tried most of the practical avenues and has drawn a blank. Maybe the house was never bought, maybe money never changed hands, maybe the house was bought but put in someone elses name. But if the house was bought, then there will be a record some where - maybe in the father's solicitors office?
In reality, the question will be - how do we sort out the title so that should we ever want to do it, we can sell the property? So, that means either locating the deeds by e.g. advertising or trawling through all the solicitors that might have acted or are in the area and if that works out then registering the title in accordance with the will. Or if that shows nothing then an application for first registration can be made in the Land Registry. If the land is registered, that is a good start but that does not seem to be the case as a search has not shown anything. If the land is unregistered, then the application will be that bit more difficult.
See a solicitor.
mf