We've been living with no real downstairs since November.
The living room hold-up was my own doing, but since we were able to move back in that's made a big difference.
We got a mini cooker after getting really sick of microwaving and that made a difference.
In the last place we did even worse - we had one room only and a bathroom with only joists on the floor for a few weeks.
It's doable but I think you can underestimate how stressful it is to have to walk up and downstairs to fill a kettle up, and having no room other than a bedroom to read or relax in (total first world problems obviously).