first of all, congratulations on the acceptance and interview! i would love to attend either myself.
laurafinn is the massey go-to around here. this is a quote from her replying to one of my questions.
"I'm in the midst of final exams now, so can't get into this too much, but Massey's pre-selection semester (ie, the 5-year option for people without any/all the pre-reqs) has gotten more competitive every year. Nowadays I believe 1 in 4 international students who start the pre-selection semester are accepted. I think they may have capped the number of international students who make the attempt (that's the rumor, get the facts from Massey administration!)
It's a high-stakes gamble and thus very stressful. Plus, your grade is based largely on your final exams, so you don't really know where you stand until the bitter end
Email Massey to verify, though. It's been years since I did pre-selection."
IMO you should think about what school you'd rather attend based on other factors, forgetting about the $ and the pre-selection dilemma for the moment. both offer such different experiences, is there one that stands out to you or that you wouldn't want to miss out on?
also, you have to think about what kind of student you are. pre-selection sounds scary to me. have you been in a rigorous upper level science program lately and done extremely well, like top 5-10%? and have you lived overseas before and are positive you can deal with the stress/homesickness/new stimuli, etc.? if these are true, you have a better chance of getting into massey's regular program. or will you be distracted from competing by the cool new country you are living in? or are you a comfortable well rounded A/B with some Cs student? maybe you would feel better about the gamble on getting into glascow.
and one more thing about the 10k/year difference. that's in tuition alone, i think? if you factor in living expenses and plane tickets, is it more expensive to fly to and live in nz or the uk?
congrats again, you should be happy!!! and this is one of the best agonizing decisions you could be making