Read up on what those other countries are doing. That's what we should be doing. And also replacing Trident with something else because it's shit.
Also it won't be a nuclear war (unless North Korea decides to start it, which seems unlikely). It will be more of what we've seen already, drones and targeting energy and water supplies, and cyber warfare, and more powerful regular missiles.
The countries that have the manpower, weapons and money to start a nuclear war are Russia (who won't do it because they're old school in their fighting and don't actually want to destroy places beyond repair, they want to take them for land/empire), the US (who won't do it because they're not immediately threatened geographically, can't justify the cost to the US people for fighting foreign wars, and are like the Airbnb/Uber/Amazon of war because they just use other people's bases, they don't own their own stuff in the rest of the world), China (who won't do it because they prioritise the economy and war would kill it off, they will be happy to supply to both sides and remain relatively neutral in someone else's world war though), and India (who are focused on a population growth and development strategy and don't really care about anything outside India).
Iran, North Korea, etc., are all too small to actually start something, they wouldn't be able to finish it and they'd be decimated.
But it won't happen this year unless Israel loses its mind. There are too many elections happening to interfere in and that's what will be distracting everybody (over half the world's population is going to the polls this year).