With an NHS Pension you don't need to choose to reduce your annual income pension for him to get a survivors pension. He will get one automatically.
I see thinking about this as a scenario planning exercise. So, thinking about the what ifs. What if you died tomorrow, how would family finance work? As pp said, would mortgage be paid off by life insurance plus death in service benefits? Would he need to go back to work to feed the family or would your survivorship pension be enough? How would that work, would the kids find that really tough in those circumstances, losing him to work as well as you?
What if you died shortly after retiring? Would the survivorship pension be enough for him? What are your relative ages factored into this - ie would he have a gap before state pension for him too.
What about if you become ill and have to medically retire but don't die?
The other thing to consider is when you want to retire. Different sections of the nhs pension have different retirement ages. So you might be able to take some pension at 60 and some later at 67/68/whatever state retirement is when you get there. You can use a private pension to build for yourself to stop working at 60, to cover those years before state pension and the rest of the nhs pension kicks in.
A private pension is basically a tax efficient way of investing, with certain withdrawal restrictions, linked to age but that probably has impacts on other pension features (lifetime allowance etc, I'm hazy on this stuff - it doesn't sound like a massive issue here). It also has some inheritance tax advantages if you die at certain ages I think (ie young). Your NHS pension gives good annuity, but dies with you and spouse and kids (they get a pension too if you die young). A private pension can become assets to pass on so you keep it all.
In pure income post retirement terms, if he isn't going to work after the kids are 12 he should buy NI credits before investing in a private pension, it is far better value for money, so he gets the full state pension. That would be first priority before private pension, as he would want that in retirement.
But you are right to question why you are saving if you don't need to. Think about why this advice might be important for you or not in terms of scenarios. You could pay a one off financial adviser fee for a tailored review of your full finances. Possibly worth it for peace of mind as this is not a thing to cock up, you can end up with big avoidable regrets.