I tried Manuka honey recently for digestive problems and did a fair bit of googling research beforehand. Apparently to be be accredited with medicinal properties the honey must have a NPA or UMF rating, the higher the better (and more expensive). I plumped for the Rowse honey at Tesco, which is relatively good value at £17 a jar
and gets good reviews.
Manuka doesn't have to be from NZ - there is even at least one producer in the UK now. But the accreditation is vital.
I have to say it didn't help my problem, for which I was quite relieved at the price. One jar was only lasting a week at 2 or 3 teaspoons per day, and some users recommend a tablespoon daily! Good old cheap green tea has proved more effective for me.
But I did smear just a little honey, with a plaster over, on a little sore on my back, and it cleared up in a couple of days.