The calculator is good at number crunching but it doesn't take all the individual circumstances relevant to your case into account. If you wanted to copy and paste the figures into a post we could give you an idea how accurate it is.
I'm not sure I understand. Quite nervous of doing much on this in case husband has same idea. Individual circumstances are married for 11 years, two children under 5. He left marital home and I am still there. He rents a place and sees the children but they do not stay with him. I don't work. He does and earns substantially.
I have asked him for an allowance that for the moment covers everything from mortgage to pint of milk which amounts to about 28% of his salary although he is on a basic and the rest is made up of bonus.
All I ask of him is to take care of school fees. Does this help?