An Easter in April on the north of the North Island, is likely to be quite pleasant, with luck there are swells being generated. So a few cool night type clothes but mostly early Autumn temps.
The east coast has gentler waves with a a few epic bar surf spots and the west coast I would look as far up as
Aripara .
Easter both in Australia and New Zealand is a peak holiday time when the parks, resorts and holiday Baches are full so book , you may find many spots already booked out!
All of New Zealand is pretty amazing. The Kauri forests of the far north, various hot spring and Maori villages.
A lot is south of Auckland , volcanoes, snow capped mountains and Hobbit country. There is surf all round the coast, but really check a New Zealand travel guide.
Ther is a beach on the Coromandel peninsula where you can dig your own hot water spa in the sand after a surf!
Curious, does something oblige you to go north?

I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun! 冲浪爷爷