I’ve used credit cards for over a decade to buy cars or undertake home repairs etc.. I have two accounts that both offer 0% on balance transfers or money transfers on a cycle for 12-18 months, I just repeat the process until it’s paid off. I pay a small fee but never any interest. I also pay into my kids bank accounts every month. In many cases it’s the cheapest loan option available.
If everyone just focussed solely on paying off debt (CC, mortgage, loans, HP, store credit) it would be imposible to do anything in life. The OP is steadily paying off CC debt, the OP is aware and conscious of overspending and addressing it. The OP saves for her children’s future and is borrowing £100 until next month as Christmas is expensive and visiting family is important.
Using this money now is literally no different to depositing it into their accounts later than planned. I’ve got a couple of envelopes sitting on the mantelpiece with lots of Christmas money from relatives for the kids. My older ones get to spend it now but my youngest I will put in her account. I haven’t done it yet because I’ve been busy. If I needed £100 in a hurry for something I’d take it because it makes no difference, I’d still have to keep the cash and transfer it from my account eventually anyway. So why are people ripping the OP to shreds?
All the people saying you’ll never ping it over to them, I don’t know what circles you move in but I always do. Sorry if you wouldn’t but that’s your problem.
OP well done for putting a bit aside for your kids. I did the same even when times were tough and I went without things to put a little bit by each month for them. They know they can only use it for travelling, moving out or towards a car and they accept this without question.
They also knew from a young age that if they lend me money ie "whose got £10 I can stick in this card I’ve only got a £20" or "has anyone got £2 for your sister for silly sock day because I forgot" that they’ll get it back. This is completely normal in my family, I feel sorry for kids whose parents aren’t like that.