First you need to do a really, really detailed spreadsheet with absolutely everything you spend on it. Every single penny.
Next, you need to take out all expenditure which isn't absolutely essential to enabling you to work and keep the roof over your head.
So remove children activities, window cleaner, birthday parties, discretionary clothes, haircuts, gym, subscriptions, magazines, coffee out, holidays, cinema trips, flowers for the garden. Everything.
Then see if your income covers your core basic costs. House (all bills)., childcare, food, travel to work.
If you can't cover core costs then see if your mortgage provider will allow you to extend the mortgage term to reduce monthly payments.
If they won't then you are going to have to move to a cheaper place.