I do know how you feel, honestly I do. I grew up in South Africa and when I came back I wanted nothing more than to go back and have my life there ( I came back when I was 19 because didn?t have a job etc so came back when my parents did).
But I think it?s important not to look back and imagine having the life again that you had then, because the reality is that you can never go back.
To me it sounds as if you are imagining a dream, a dream of your ds having a life that you had when growing up, and to be honest that?s not how it?s going to be. When you grew up you had your family and friends, now if you go over there it will be on your own with no support, and you will be leaving your family (ds? extended family) behind (assuming they are over here and not in nz). And even the friends over there you might have left behind will have moved on and it?s unlikely that you?re still going to have the same friendships you had there before you left.
I personally think that leaving everything behind here and going over there to chase a dream that is unlikely to become a reality is mad. If you had the offer of a job of a lifetime then it would be different, but you can study anywhere. And you can go there for holidays with your ds and if as he grows up he decides he wants to be a kiwi he could always go there of his own accord or you could move when you?re in a better position to do so.
But if you go now then you?re going to be stuck there for the duration of your degree, because flights home don?t come cheap, so what is going to happen to the relationship your ds has with his grandparents etc? Having moved away from mine when I was 5 I can say with some certainty that that relationship will be broken.
I wouldn?t change my life for the world. I loved South Africa and I?m so so glad that I grew up there, and I still see myself as more south African than British. But now when I look back I try to do so with my eyes open. And although I see the bbq?s and the outdoor lifestyle and the lovely summers and the beautiful country, I also think of the fact that public transport isn?t safe, that we used to drive down to Cape Town with a gun in the car, that people have bars on their windows and safety gates on their doors, and although I would love to go back there for a holiday and I want more than anything to take my dh and ds there, I wouldn?t ever go back there to live.
How ever wonderful NZ is, it isn?t all wonderful, but it?s much harder to see the bad bits when you look back and remember the good bits.