This time of the year its daylight until 8:30-9:00 pm, so driving is not an issue
I would recommend going to
Akaroa direct from Charing Cross. The Canterbury plains are very flat. Akaroa is in the Port Hills. Just head for the hills east from Charing Cross (Charring Cross-Burnham-Springston-Taitapu-Motukarara-Kaituna-Akaroa). You cannot go wrong as there is only
1 road on the southern side of the Port Hills. The Port Hills are visible for many miles.