Don't become his maid just because he's working from home and you're there not working. He can fetch his own dinner and cuppas just as he would in the office. It's not your job to remember where he left his xyz, he can learn to put it somewhere he'll remember or look for it himself. It's also not your job to tidy up after him, following around putting the bread back in the fridge, the tools back in the toolbox, hoovering the mess on the floor after he's done xyz or picking up towels/clothes from the bathroom floor. Even small children are taught to put away their toys after use, he can clear up after himself.
AFAIK HMRC sets the amount for NI including voluntary payments. You don't gain a different amount of pension or other benefits by paying in a higher amount. Claim child benefit in your name, you'll then automatically get NI credits. If he earns too much for you to be entitled to CB it'll be deducted from his wages by HMRC (think that's how it's done, he pays it back somehow anyway).
For the personal pension the amount paid in should mirror his, to be fair. So if you split you're on equal footing. If you don't split then you'll be richer as pensioners. This might be quite expensive because his employer may be putting into his pension too. If you're not paying in equal pension amounts, you could put you down as a higher percentage owner of the house than he is eg 70/30 split or whatever.
Anything you save isn't technically yours even if the account is in your sole name. In the event of a divorce it's a marital asset, so potentially half his. Just something to bear in mind if one of you is a spender and the other a saver. No point denying yourself things and being ultra frugal only to end up losing half of it in a divorce. So if you are financially very different in your attitudes it's worth considering whether being married is right for you, if you're making things fair financially anyway.
If you're in an unfair situation eg not working, no pension, don't own property - while he's furthering his career, building a pension and paying off a mortgage - it helps to be married so if you split you get some of the house, pension and savings (if applicable). If you're not married but you're co-owner of the property, have an equal pension pot and children's/household/ordinary life expenses come from his wages, then anything you save up from your share of the spare cash remains yours even if you split.
Do you have a job or a career? Will it be impacted by taking a break from working? That's something else taken into account if you're married and split up but not taken into account if you're only cohabiting.
He still needs to do something round the house. His role doesn't end with a 9-5. Children/home may be mostly you if it's your "job" now, but you can't be expected to be "on-call" 24/7, you need downtime too and "time off" if you're ill. He doesn't get to become like another child for you to look after. Also when he retires or you return to work, he has to step up and share tasks.