Apart from 'Art Deco' buildings and general tourist stuff, Hawke's Bay doesn't offer much for folkies except a Wednesday night session at The Rose and Shamrock in Havelock North and even that is turned off when sport is on - for example, World cup rugby.
As Chris has suggested, check the Kiwifolk site - here.
As long as you start in Auckland, contact Roger and Hilary at Devonport and go from there.
Robyn