My thanks to everyone for your very helpful information. Nice map links--wish I could bring that feature with me. Charing Cross, interesting to see the 7 roads in a "wheel spoke" setup. Mwenenzi, what a coincidence that your parents live in the same area! Yes, the Stoneylea farmstay is described as a 364 hectare sheep & cattle farm. One thing I have surmised from everyone's input is that we'd better be sure we navigate that area in daylight!
Hope to touch base with chchkiwi. I'm thinking if I can handle driving Hwy 1 Big Sur in California, we should do fine getting ourselves to Akaroa. Hard to know when someone describes a road as winding and perilous, what they're comparing it with & how much driving they've done on mountain routes. Kiwi Flyer, thanks for the suggestion for our drive while in the North Island (as well as Nelson-Christchurch). I'm printing out all of your ideas.
Leaving later on today.