Many people have fitted a Cooper S bonnet onto a One / Cooper, it just drops into place. You can't just fit a scoop to a Cooper bonnet as the entire bonnet pressing is completely different.
However, I would think twice before placing an otherwise useless "rain scoop" just above the engine
Less of a problem on your "D" than on a petrol engine (with HT leads), but still just a source of unnecessary potential problems.
Tigger.