I don't know if he's still flying, but John Howells used to be one of the best helicopter Ag pilots in Oz. He used to be in Gatton, QLD so maybe a websearch, or even the yellow pages might help.
John McDermott was another ace, also in QLD but he sprayed in Scotland for a few years as well. Last I heard he hurt his back in a crash a few years ago but I don't know what happened after that.
Zeb