Please ignore if you already know these but here is what i can think of right now.
Oven based tips:
Batch cook- filling the oven means it uses less time/energy to heat to the right temperature. It also means it is on once for several meals rather than each time you have dinner. Freeze in portions.
Turn the oven off five/ten minutes before cooking is done.
Put an oven dish filled with water in the bottom of the oven whilst cooking dinner. I doubted this but it actually heats up really well which means you have hot water for washing dishes without any extra energy being used. (Ignore if you use a dishwasher.)
In winter after cooking leave the oven door open to heat the kitchen. You could even stand a clothes horse in front of it to kick of laundry drying or finish off what was on the line during the day.
Laundry tips:
Half the powder, lower the temperature, lose the fabric softener (use a couple tablespoons of white vinegar if you miss the softness)
Downbrand on the powder. I use the asda one and it is grand. (Ignore if skin issues make this not an option)
Dry outside as much as possible.
If you cant dry outside, some things will dry on a hanger on a curtain pole by an open window. Use banisters for towels/bedlinen if you have them- heat rises. If you have an airing cupboard with hot water tank, use it. If there is room see if you can rig up a miniature sheila maid in there. If not rig a normal one in the space above the stairs (if applicable)
Wear things until they are actually dirty/smelly (except knickers 
)
Things air out really well between wears on a hanger on a curtain pole at an open window.
Those over radiator hangers can also hang over windows on the outside if you have no outside space to dry. Peg everything on them though or you'll be chasing your keks across next doors garden
Energy tips:
Get into habit of switching everything off at socket when not in use. TV, internet, PC, chargers, microwave, kettle, washing machine
Fill kettle in morning and boil then fill flasks for tea/coffee/washing dishes throughout the day. Switch kettle off at socket.
Dry hair naturally where possible (if applicable)
Have one day a week "energy free" where everyone uses the bare minimum. No TV, internet, radio, straighteners. I tried a week recently and it was too ambitious but one day a week is doable and will saving a couple of £ a week. (Or did for me anyway.)
Lights. Take the bulbs out of lights where you dont really need them. I find we switch on lights out of habit because it is there. If a light is needed try a low energy lamp instead.
Money:
Use YNAB app to track spending.
Every evening you and DP take all the change under 50p in your wallets/purse and put in a jar. At the end of the month this is your treat money. For ice creams for everyone or a take away if there is enough. If you dont use cash then set up an account and transfer it in online banking. I transfer whatever is left over the pound. So if balance is £61.72 i transfer the 72pence. Im getting around £20ish a month as a lone parent so could be a good way to save for treats as no-one misses the pennies.
Sorry i cant think of anymore now. Hope some of these are helpful. If i think of more i'll update. Best of luck OP. It sucks being this skint.