Ok, so, suggestions as follows. My questions are not questions to get an answer, it's just questions for you to think about yourself.
Rent: Is this a safe £400? If your landlord is likely to put it up soon then work it into your planning.
DMP: Is this debt mgmt plan? Stick with it... how long have you got left? Are you accruing interest or charges on the debt? If so it might be better to use your savings amount to clear the debt faster.
Kids classes: Are they really into all of the classes? (If yes, keep them) Are there any they are losing interest in that you could drop? Or, do any of the classes offer a subsidy fee for parents with financial struggles?
Car insurance: Have you done an online comparison recently to check if there is a cheaper deal?
Gas/electric: This will rise for everyone. Same question again, have you done an online comparison recently to check whether there is a cheaper deal? Are there ways you could be more frugal - wear jumpers before you put the heating on, are you using all of the hot water you heat, run your washing machine etc at night if your supplier has an off-peak.
Water: Are you on a water meter? Could you be more frugal with water usage? Shorter showers, half a bowl for washing up.
Prime: Would you really miss it if it was gone? Six months without it gets you an extra £50.
Food: Do a food plan for your three meals per day plus any snacks and drinks. Buy exactly what you need each week.
Petrol: Well, we might not have any soon
But are you using the car for any journeys that you could actually walk instead?
Phone/internet: As above, do an online comparison to see whether you can switch to a better deal. I've just switched my phone to virgin for £6/mnth and broadband with Sky for £25/mnth.
Savings: It's brilliant that you can save but as above check whether it would be beneficial to use this to clear the debt faster.
Maybe you also have council tax, tv licence? Go through your bank statements for the past few months and list every outgoing, then pick out which are essential and which are nice but not essential.
The top-up shopping, whatever you are topping up on, add it to your weekly shop so you're not needing to go shopping multiple times.
Eating out: Can you cut this back? If it's to meet friends can you meet for coffee instead of food, or get a take away in, or find special offers, or go for a walk for free? Or just be strict and not eat out for a few months?
Toys for the kids: Could this be cut out until Christmas? Maybe arrange a toy swap with their friends so they pass on anything they are bored with and get something different?
Days out: Look for free things, special offers.
Bits for the house: As with toys, can you set yourself a challenge not to buy anything until Christmas?
Your income: As I suggested before, have a big clear out and try to sell on things, a few £s here and there adds up each week. Then your business, you have an online shop? Is this business something where you can get a boost from Christmas/seasonal? Like, suppose you are making mugs, are you now making Halloween mugs, then bonfire night mugs, then winter and Christmas mugs. Are there local websites, facebook pages where you can promote yourself more? Are there local events where you can have a stall and sell a bit extra in person?
You might well have already thought of all of this. I really sympathise with your situation. I was in debt and living hand to mouth for a decade, it's hard work. But small changes over time does benefit, as with being strict with yourself. Good luck 👍🏻