Hi Ann,
There is little problem finding places to change money on this tour. Travellers cheques (sterling or dollars) are very secure, and a bit of cash too. Probably the hardest place to change money is the US, so for these 3 days you'll need some dollars cash plus a credit card or dollar travellers cheques.
The weather should be fairly warm throughout, but you won't regret bringing a waterproof jacket (New Zealand gets a lot of rain) and maybe a jumper / cardy. Dress is pretty informal everywhere we go, but it's nice to have something smart for the odd night out.
The trip is fabulous - be prepared for a few long days on the coach as we really do pack a lot in, and don't forget your camera!
See you at Heathrow next week, Judy (tour manager)