To use the kids Christmas money to get me through January?

I agree. I bet the OP wishes she hadn't asked, given how many posters have jumped in to shame her.

Great to build this for them long term but in short term more financially astute to clear debts first.

There is more than 1 week in a month.

If it’s essential for your survival, I’d do it. Pay it back when you can. x

Do what you need to do. I would have done this when the children were small. They've been paid back.

Stop guilting her for a perfectly normal cash flow issue.

Maybe in your world but not in most.
Having £30 left for food is not a normal cash flow issue after Christmas on a 'good income' as she states.

ive borrowed cash off my kids when they were younger to get by, whether that be food petrol or a bill. I’ve never felt guilty for it and always paid it back. I don’t understand the big issue.

Agree!!!! You said you're paid well, so obviously haven't managed budgets. And worried about spending on the credit card. Then don't go.

If you can possibly do it, keep up the regular savings for the DCs. We saved £100 per month for each and when DC1 reached 18, their CTF was worth £37K.

She's probably skint because she gave the kids a nice Christmas! Come on people, the woman isn't lounging at a spa paying a gigolo! She's trying to fuel her vehicle to get to a family NYE!

Stop guilting her for a perfectly normal cash flow issue. The pre-school children aren't going to miss the cash.

I don't understand the cost of your fuel.
£70 in my 2 ltr car would last me 250-ish miles at least.

You say your trip to work is 9 miles. if that's each way that's 18 mls x 5 days = 90 miles- plus 40 miles to the in laws.

That is not £70 of fuel.

The trip you mention we ‘can’t afford’ - yes, we need fuel, but then the children also will be fed and entertained for a day so it balances out

Another example of you not understanding money.... feeding and entertaining two toddlers won't cost £70 for a day, so it won't "balance out".
I do get that seeing family, esp grandparents, is important. But do really you need to be the ones to travel? Can they come see you?

January is a tough month. The kids aren’t aware. Borrow it if it makes life easier and you can pay it back.

This. It's fine. Don't stress over it.

I’ve done this before and always paid it back, I wouldn’t have considered it if paying back was going to be a problem the next month but it was obviously top of the list in terms of “bills” to be settled. January can be more complicated as I always get paid early, it’s a costly month and I’ll have above 5 weeks until next pay day. The “If you do this you know the kids will never see it” comments are not my experience at all.

RTFT They are under 5 years old. Not likely to go to the shops.

I always take the kids’ cash. It’s useful to pay the piano teacher etc. I always tell the kids though and they never forget to remind me to transfer over. Tell the kids then you’ll feel better about it.

Kindly, OP, you need to talk to someone about money.
Maybe start with the CAB or look at some advice online or apps. Money Saving expert etc.

Being blunt, you have a bad credit rating and credit card debt. So this is a long term issue. You admit that you would 'go mad' using CC spending hundreds, which is why you stick with cash.

So you're either an impulse buyer , spending on things you want rather than really need, or you can't 'do the maths' and budget.

You are prioritising savings for your 3 years olds, leaving yourself short each month, which is madness.

Your children have years ahead when they can study and earn their own money.

No mortgage? Are you renting? Is a mortgage out of reach because of no deposit? These are the priorities - not kids' savings.

Use the credit card what if the kids want to spend their money?

That's even more reason why you need to stop putting money into the kids ISAs for now.

You can't afford to be saving for them when you not only have debt, but an unexpected £100 loss is this much of a problem for you. You need a buffer.

I've done this before - as long as you pay it back at some point it's fine! They won't even know - and petrol / food on the table is to everyone's benefit. When my kids were younger sometimes I had to take the money I paid into their savings each month back out again as I couldn't afford it - better than starving. This time of year is always tight. Even if you paid back a tenner a month between now and the summer it'll be fine.

I well remember being so hard up that fifty or a hundred quid would make the difference between getting to the end of the month and not. And with two kids I think that food on the table is more important than their savings

You are not a monster for considering doing this, it is just sad that you are having to. Good luck.

if it gets to be a habit perhaps give the GPs the children's account numbers

actually 😳 bloody hell

The number of people saying it's fine is astounding.

Moral test is this.
Would you tell PIL that you had done this? If not, then no. If you'd tell them then crack on. Fairly sure I know the answer.

The bottom line is, it isn't your money.
You are effectively stealing from them (albeit with the promise to lay back, but what if next month another surprising bill lands??)

Take your own scenario out the question, and look at it like this:

You care for an elderly neighbour, you know she has £100 in a cupboard that she won't access for a few weeks, it's just her secret stash. You need £100 to pay bills. Do you take from your elderly neighbour knowing you intend to pay it back (without telling them) or would you never dream of it?
If it's the latter, then sounds to me like you need to spend the extra on the CC, and do some hard firm wallet workouts for 2025.