Probably all been suggested already, but my money saving tips:
cold lunches and breakfasts (saves on electricity)
cooking dinner in slow cooker rather than the oven or eating salad.
when contacted king pasta or rice, bring the water to the boil, add the pasta or rice and then switch off the gas. It still cooks perfectly, just takes a couple of minutes longer. No need to simmer it for 10 minutes.
meal planning, and shopping just once a week.
packed lunches.
foraging for berries in the autumn and freezing for use over the winter.
washing laundry on cold 1hr cotton cycle, turning spin speed to lowest setting during summer.
Air drying outdoors year round.
quick showers.
using a ‘baby dam’ to reduce the capacity of the bath for the youngest.
everything switched off (ie not left in standby) when not in use, led lights on sensors.
hand washing dishes once a day rather than using dishwasher.
one super basic/budget dinner per week (I aim to keep our weekly grocery budget to £75 to feed 5 of us)
buying bulk washing powder - works out to 10p a load rather than 22p per load that we were paying for SMOL
walking rather than driving if it takes 30min or less to get walk somewhere.
For the winter we will be having a philosophy of ‘heat the person not the house’ and have invested in thermal vests, Oodies, fleece onsies, thick socks, slippers, hot water bottles and heated throws for everyone.