That depends on who'd be flying out to New Zealand - or to the UK for that matter. It's not like they'd bring the TARDIS console room set to NZ to shoot scenes. OTOH, they could build a console set that looked like the inside of a Hobbit hole, just for the occasion. :P
Speaking of which, if they secure a stupidly rich man like Peter Jackson a a director, who's to say that he couldn't open his own pocketbooks to get that extra helicopter shot of Capaldi and company walking over those snow-capped mountains for an extra twenty minutes? Or does the BBC have rules against that sort of thing?