I dont know the answer to your question about benefits. But I’d be very careful with your plans . You say that “ your plan “ is to parent 50:50. But what is his plan ?
Many men will say that they intend to have their children 50:50, so they don’t have to pay child maintenance. But very very few actually have their children half the time and even fewer do half the parenting.
Is he doing more than half of the childcare / parenting / wifework now? Because if not that’s not going to change after the separation.
Most non resident fathers see any time they spend with their children as “doing a favour for their ex “. They see it as something they will fit in when they can, as a time that suits them when they are not doing anything else such as socialising or working.
Many men start to date again / move in with someone else very quickly, and often stop seeing their children as much .
It’s also common for them to move some distance away to avoid doing any /much childcare , then refuse to see the children unless you transport them both ways .
Im sure you think that none of these things will apply to your husband and I hope you are right. But I’d caution you against making your plans on the basis that he will have the kids half the time and pay half the nursery fees. Because you are the one who will pick up the slack if he doesn’t.