You say that you can't see where you can cut back, but without the full picture, it's impossible to say, but I'd bet that you could make quite a lot of savings.
Eg, you mention food at attractions ('gosh don’t the kids add up. We went to a trampoline place the other weekend at it was £50 all in by the time you added drinks and sandwich') - this is an obvious place to start. It's almost always expensive for poor quality at the end of a long queue. Even if you can easily afford it, it's an unattractive choice if you think about it. Eat at home before or after, take a picnic/snacks, eat somewhere else on the way. Loads of ways to avoid paying a fortune for shit food.
For days out, look at discounts, almost always ways to get it cheaper. Look what memberships and annual passes are available and rotate round so you do different ones over time - National Trust one year, English Heritage the next for example. That gives you access to country parks with free entry where DC can run around. Or free parking at the beach - see what's available where you can easily travel to. Take a picnic of course.
Your DHs attitude to money sounds problematic. And without a review of your spending, it's likely you'll always feel like you're struggling, because you're always fire fighting, rather than planning and being mindful about your spending.
Can you move your money into different pots and accounts so essentials are covered, tax, large purchases, emergency fund and annual and irregular things like Christmas, holidays, insurance, car replacement etc is covered and then you have a pot of money remaining that can be divided for family days out plus some personal money for each of you? So you'd have money for new boots etc.
Have a look at Moneysaving Expert budgeting advice, but without getting your DH on board, he could be undoing any good work faster than anything constructive you're doing.
https://www.moneysavingexpert.com/family/money-help/