Arches B&B is a lovely unit just outside Twizel. Tania and Gordon provided everything you could need for a few nights stay. We had fresh eggs for breakfast, nice comfy bed, great shower, wifi and TV. They even gave us the use of their bikes while we were there. It's a bit of a walk to the town centre, where there are a few restaurants- Poppies cafe was the best we tried.
Highly recommend booking Tania's place for exploring Mt Cook area.