Thanks all.
No, craning over other properties is not an option I'm afraid.
Yes it has PP, but not for what I want to build so I will need to make a new application. It is all flat so no issues with fall for drainage etc.
Sorry, I should have been clearer - the narrow road is the first that you come to when you turn off the main road, the wider road comes after. The main issue is the right angle turn from the 3m lane into the 6.5m street that the plot sits on - there is no pavement or other wiggle room as the walls of the adjacent buildings are right on the street. If the vehicle delivering the materials was less than 3m wide then it could park across the T junction and a tele-loader or similar could take the materials off and trundle them up the 6.5m street to the plot, but it would require neighbours to park elsewhere and so on so it couldn't be done every day or without some pre-planning.
That is interesting re your kit house Dave, thanks for that. Do you happen to know the maximum distance for piping concrete? It might be possible to bring it from the next street over but distance-dependent. Failing that it would need to be mixed on site, yes.
I am meeting an architect on site next week who I can discuss some of this with, but practical advice from those who have faced these sort of issues is always valuable. I haven't discussed price with the seller yet either so obviously all these sort of potential difficulties, while challenging to work through, might help to keep the price down.