Like anything your perception is skewed by the circle that you live in. Everyone that I know is very interested in conservation. My family votes national and are farmers and put a lot of effort into managing their stock and planting around their waterways. My friends are all urban and vote green or labor, they also put in a lot of effort into the environment.
Everyone I know recycles, uses eco and environmentally friendly products where they can, etc. People who I know who fish always fish within the allowed limits and quotas. My grandmother told me over Christmas that she was never going to use another plastic bag.
So, in my opinion, the country is very eco minded, but that sample is skewed because it's only my friends and family. I did meet someone at a party a few years ago who said she just threw her rubbish over the fence onto a council reserve because she was too busy and lived a too important life to bother with dealing with it. There are also people who regularly get caught taking too much paua, or catching underage fish, etc. So obviously they're out there, how prevalent people with disregard to the environment are I don't know, as I said I live in my own bubble.
It could be that people in the UK are more environmentally minded than here, but that wasn't my experience when living there. It could be that they're not but the people that you've met in both countries have simply given that impression.
Someone has probably done a study somewhere.