We went through almost every conceivable arrangement with the children from my ex living close by and the children visiting him on a daily basis when he wasn't away working to my ex moving 400 miles away and the children commuting every other weekend. TBH they all work fine if there is flexibility and at least one parent has a can do attitude.
It's important to see a solicitor to find out where you stand and what options there are in your particular circumstances. The experiences of other posters can't be relied upon because each case depends on the specific details.
Xenia's circumstances I believe were similar to mine with assets in 7 figures, incomes in 5 figures and husbands who earned less. In those circumstances the needs of both parties can be met so there is little justification to move away from sharing assets 50:50 and the higher income spouse may be required to pay spouse maintenance.
It very different when the value of the assets and incomes are more modest. There is no law in England & Wales that assets are shared 50:50 or at least it's an oversimplification of the law. When there aren't enough assets to meet the needs of both parties there is a checklist of factors in s25 Matrimonial Causes Act 1973 to refer to. It isn't possible to just read the checklist to understand it but basically the welfare of children is the priority and the needs of both spouses comes near the top of the list.
Divorce settlements are about balance. If the children are to live with you most of the time you will "need" a more substantial property than your husband who will only have them staying every other weekend. He will still need somewhere adequate though and if he earns less his mortgage raising capabilities will be less than yours. So a good starting point is to consider local house prices and both parties' mortgage raising capabilities.
Spouse maintenance is usually only appropriate when there is a big discrepancy in incomes and the higher income spouse earns above average.
About the point of releasing your husband from the mortgage. A family court may order the transfer or sale of property, but the court does not have the authority to order the mortgage company release someone from the mortgage.
That means in circumstances when Spouse A can't raise enough mortgage in their own right the Spouse B may need to stay on the mortgage until such time Spouse A can release them. Keeping a roof over children's heads is the responsibility of parents, not relatives or grandparents.