Start out by listing all your direct debits. I have loads more than you have listed. What about the following:
Life and critical illness cover
Building and contents insurance
Broadband
Pet insurance
Car tax
TV licence
Do you pay anything for your kids? After school clubs, activities, pocket money.
You make no allowances for clothes, dentist, opticians, gifts, vets, holidays, days out, socialising, etc
Do you ever eat out, socialise? Do you buy books, music, toys? Do you go on holiday, to the cinema, days out? Opticians? Do you buy prescriptions?
When you factor in some of these things that are ad hoc spends, you start to see where your money is going.
Keep a log for a whole month of all your direct debits and then everything you spend in addition. It can be quite eye opening.
Your water is high and I would look at getting a meter. Food also seems high but it depends on the age of your kids. Sky and phone are also things to look at. I have just ordered an iphone 17 and will be paying £30 for that and £10 for my sons contract (he is getting my old iphone 14 for Christmas).