I'm so sorry OP because it sounds as if you're living in a very difficult marriage (by refusing to talk about it and referring to 'your real world' not MN world.
It's very odd that you've not mentioned any JOINT responsibility for all of this.
eg- no family car? Just YOUR car that needs fuel to go to his PIL?
I sincerely hope you're not suffering emotional or financial abuse. Please call Women's Aid if you are.
Look- the money you're putting in the kids' ISAs.
It makes no sense.
You're paying a huge amount of interest on your CCs. Wasting money.
You need to clear debt first. This is BASIC.
If you want you give your kids some nest egg when they are adults, there are many different ways to do this. You can save up to £20K pa in your own ISAs that may have better interest rates. Then you can hand over what you can afford to your kids when they are older- like going to uni or buying a car.
I'm trying to be helpful here and kind but naturally it may hit a nerve because you're really struggling.
If the only reason you're putting money into a kids' Isa so you can't touch it- can you see that's very muddled thinking and shows you do have a serious issue with money? Something has made you spend more than you can afford, presumably for a long time. you do need help to figure out why. Is your H withholding money? Is he drinking , gambling or taking drugs?
Something's going on behind all of this.
If you don't want to share here, talk to someone in RL.