No country will do it with nuclear in the future, because nuclear won't be competitive.
If we have a week of that weather Mad Max will be a become a documentary.
This is the solution, but currently only operating at a small scale. This is something that can be scaled up insanely quickly for a fraction the cost of alternatives. The success of this relatively small installation has already resulted in many more battery projects coming online this year.
This being my day job, it would add $8k to the electricity bill of the two child household in Australia if we used your solution to store the wind and solar power.
I ask because a 40C day sounds like a problem due to AC usage, but would probably come with pretty effective solar, and decent wind near the sea.