Your budget does look tight but, as someone else has already mentioned, you could shave a few pounds off by switching your broadband to a social tariff.
Could you go SIM only on your mobile to cut the cost and keep your current phone. No-one needs to be paying £20 pm these days, you could easily get it down to about £7 pm then for a phone, get a cheaper Android and look for deals. My last two phones have cost £100-150 in Black Friday deals and I've sold my old one for about £60 on ebay, that's after about 3 years, so my mobile cost is about £10 pm in total including a perfectly decent phone and several Gb of data.
Look on Moneysaving Expert and sign up to the weekly newsletter for tips on making extra bits of money, eg switch your bank account every time there's an incentive and you can get £150 - 200 each time. I've done this a few times, so made around £1k. Also look at the Energy Help section - you might be entitled to a grant, as the money you're paying isn't enough to put the heating on properly.
If your credit card is not on a 0% deal, switch to one that is.
You can get slightly cheaper breakdown cover from Autoaid or GEM - it's about £70 but you do have to pay for it all in one go. But it might be worth trying to have a really frugal couple of weeks (little as possible on food, petrol etc) to free up some money to pay for it, to reduce the ongoing cost.
Do you actually need a TV licence? If you don't watch live TV or use iPlayer, you don't. You could get TV using a streaming service, Now TV entertainment is probably the cheapest one, as you can always get a deal to reduce the cost.
On the matter of your DS's father cheating on paying maintenance and taxes you could offer him the choice of reporting him and his mate's firm to HMRC if he doesn't pay the correct amount.
When will the loan stop, this will help quite a bit.
But if you're really struggling and the loan has a way to go, you could look at a formal debt management or even a debt relief order but that would depend on the value of your car not exceeding a certain amount and it would force you to live without credit for some years, so it may be preferable to struggle on so you can maintain access to credit to allow you to do things like get your car fixed when needed.