A ze of 0.14 ohms will ‘blow’ the fuse whether it be rated at 60,80 or 100 amp bs1361 or bs 88.
I find it harsh to say a C2 as the fuse would blow in less than 5 seconds on a TN system.
However you are only allowed to rely upon the distributors fuse where they allow that it can afford protection to the part of the installation between the origin and the main distribution point where overload and fault protection is provided at your DB.
So if they only allow 3 meters then you need to code accordingly in my opinion.
As for 16 mm on a 100amp fuse.
My opinion is that is the demand of the installation at time of inspection reveals that overload isn’t likely then I’d assess it on that basis.
If the demand was to change in the future then before any alterations in the future by an electrician, they would need to assess the existing demand and decide if it is acceptable to determine if the proposed alterations comply Which is what’s always required anyway.