Do you have one card at a better rate than this one? A high interest rate like that is going to spiral. You can say you're fine with it but you really are storing up problems for yourself.
If more credit is no longer an option, what will you do if the boiler breaks or the roof leaks? It's okay saying this is the minimum level of day to day life I will accept but if something goes wrong you'll be much more impacted than buying clothes for a toddler on vinted for a few months.
In your position I would have six months of serious belt tightening and try to chuck every spare penny at the high interest card.
You may also need to be clever in the way you spend if purchases are available on the lower rate card - but this requires discipline. If you need to spend £50 do so on the lower rate card and immediately pay £50 off the high rate one
At the moment yes your debt is manageable but people are trying to warn you that once your minimum payment does nothing more than cover the interest, it soon gets out of hand.
Your children are young enough not to be impacted by second hand clothes, taking picnics rather than eating out etc. Deal with it now and don't end up in this position when they are teenagers and really will care. Phone every supplier of your TV, internet, car breakdown etc and see what you can shave off then put the difference straight to the card.
Make sure you always take drinks and snacks from home so there's not £15 here and there for something that doesn't really add to quality of life. Still go on the day out but take your own food so there's not another £40 on top. I agree with you that is better continuing school trips and swimming lessons but there are plenty of ways to make smaller adjustments without depriving your kids in any way.
Be utterly ruthless until summer and then see how your credit rating looks. This is absolutely a short term pain for long term gain situation.