i'm in Nadi for a few more days and would love to visit a village, meet some locals etc.
Apart from going on an organised tour, if you ask where yo are staying you may find a staff member who could arrange this for you. Generally if not going in a tour group it is given that you take a gift of kava root for the chief, which can be bought at local markets.. It may be easier to go on an organised village visit.
Suggest you check out the local tours as part of a tour, many visit a local village as a lot of the attractions are on private land and go through there on the way.