Try around queenstown if you want traditional british style singletrack holiday ( in a going to france kinda way) Many of the guides round there are brits.
Kiwis have a different approach to mtb to most holiday resorts it appears to be all short loops ( land access restrictions) or gravel grindings – ime ( from kennett bros book and speaking to the local mtb club in southland for reccomendations – as well as the moonshine ,,bannockburn classic and gutbuster races )
The scenary more than makes up for it though. We were on cross bikes and around queenstown was the only time we found anything that made us turn back – trying to ride up the river trail to the goldmine
the tramping trails are out of bounds ( and so busy you wouldnt want to be on them anyway) but the ones i did (tramp on) would have made awesome trails.
How long you going out for ?