I only bring this up again because I think most people would describe the South Island as the opposite of a "modern Britain". There is a joke on the SI that we are 50 years behind the rest of the western world. Obviously, this is joking hyperbole but it's not far off in some ways. That has negative consequences and positive ones. Those could be different for you than for me.
The population of NZ is 4 and half million, only 1 million live on the SI, and half of those live in Chch and Dunedin. The people who actually live every day in nature, who utilise the rivers and beaches, and who hunt, gather, farm and forage are small as a percentage of the NZ population. It's a bit of a myth that NZers, on the whole, are more interested in environmental issues (compared to other nations) when actually so many of them are, at best, apathetic to what happens to the environment because they are so far removed from it. You can find a community of diverse individuals who care about the environment as a sustainable resource. We have a great community of friends of various backgrounds (from farmers to hippies) who care about preserving nature for various reasons. My sister-in-law is from the Western Adirondack region in NY and every time I've been there, I've found the people, the land, the societal relationship with the environment to be very similar to NZ. The Kiwi relationship with nature isn't really different than other similar nations with similar types of activities. I will make one counterpoint, in my community, because the population is small, people with strikingly different viewpoints must live in a co-operative manner to achieve similar goals even if their lifestyle and politics are very different. However, I do know a lot of people who come from other rural areas of the SI who found that uniformity of behaviour and thought was more the norm.
I think it's awesome that you're dreaming about NZ and planning ahead. 16 is not too young!