what I use to get paid minus childcare
What is the thinking that childcare should be taken off your salary?
As the financially weaker partner it is absolutely in your interest to get married and not in his interest to do so.
As someone who resisted marriage in principle for years , I strongly encourage you both to arrange a civil ceremony. No fuss, no bother but get both of you to sign on the public record that you are now a unit for property and financial purposes.
If you really don't want to that, do a power of attorney for each other. Marriage much simpler.
s company have ensured that we as a family are no worse off financially.
That sounds good, but again I wonder why you are having childcare knocked off your former salary and how much you are paying into your own independent pension to replace the employers contribution and savings?
Good that you are thinking things through, now is very much the time to line things up to suit you.
I would also think and get agreed as s PP has said how to ring fence your own time. When he acts as sole parent, to keep him in touch with what your life is like. I work full time, in groups the dominant tone is often luck her at home all day, in private people talk ruefully about coming into work (albeit high stress technology roles ) for some peace.
If you can get everything agreed up front (and I would encourage you to arrange three monthly review to see how it's working out and make any tweaks necessary ) it can be great. Treat it like a project which demands resources to deliver to any objective rather than domesticity where the mothers demands often come at the bottom of the heap where people do often mothers are expected and valued for sacrifices