New Zealand
I would put Manuka honey on the list for New Zealand because it is the kind of thing that feels useful once you are home, not just another airport purchase. The best version is usually the sealed jar, tin or packet from a normal supermarket, spice stall or food hall, not the most expensive tourist version. The reason it works is that it gives you a quick reminder of the trip without needing to keep a fragile ornament safe forever.
New Zealand
This is exactly the sort of thing I like bringing back from New Zealand: small enough to fit in a bag, but specific enough to remind you where you bought it. Look for a boxed version with a decent date on it, especially if you are buying it near the start of the trip rather than at the airport. It is also the kind of thing you can talk about when someone asks what you brought back, because there is usually a little story attached to where you found it.
New Zealand
When I think of an easy, crowd-pleasing thing to bring back from New Zealand, merino wool socks is a good pick because it does not need much explanation when you hand it over. I would avoid the obvious tourist print and look for something with a local pattern, fabric or cut that still works with normal clothes back in the UK. I would rate it higher when it is locally made, clearly labelled and easy to use at home, and lower when it is just tourist packaging.
New Zealand
Crisp, aromatic white wine with citrus and tropical notes.
New Zealand
Kiwifruit sweets is worth adding because it feels like something you actually noticed while travelling through New Zealand, rather than a generic souvenir. I would buy a couple of packets: one to open while travelling and one to bring home unopened, because snacks have a habit of disappearing before the flight. The ideal version is modestly priced, not too bulky, and good enough that you would buy it again even without the holiday memory.