I feel your (anticipated) pain, StoneSoup. I lived through a major kitchen/dining room/ family room reno two winters ago that had my entire first floor, except the living room and laundry room, unusable. There was only one small, accessible space in the living room, and that’s where the fridge was. That was the winter of endless snowstorms and power outages, and, to make things worse, my husband was laid off from his job three days before construction began, so we were forced to share cramped spaces 24/7. We coped by doing the following: We set up a “breakfast area/living area” in a guest bedroom. We had a folding table with a coffee maker and an induction burner, and borrowed a small, dorm-size fridge that fit under the table. I stocked up on paper plates and disposable utensils, and kept a laundry basket nearby for toting dishes, pots, etc. downstairs for washing in the laundry room sink. We had a similar set-up in our partially-finished basement. That became our dinner space because there was more room for prep and clutter there. The biggest obstacle was not having running water down there. But we set up the microwave as well as another single burner. Oh, I found the bags of microwaveable veggies really helpful – the ones they sell in the produce department, fresh, not frozen, where you pop the whole bag in the microwave.
I don’t envy you, but rest assured, the end result will be worth it.