Have you listed out your budget to show ALL your spending? We did that and it's brilliant because after listing everything - annual bills, how much to spend on Christmas, etc - you can see your budget for the month that takes account of everything.
I try to see where actions can save in more than one way: batch cooking means I buy bigger packs of food which are cheaper per 100g but also save power because the reheating 2nd or 3rd time is usually a quick zap in the m/w or on the hob. Reducing laundry saves power and water but also avoids wearing out my clothes.
If you don't have a freezer, you can still batch cook to save money:
Bolognaise mix will last 4 days in the fridge so if Mon = bolognaise; Wed = chilli - add kidney beans, chilli, paprika and rice; Fri = jacket potato.
Chicken pie mix (I use the chicken and bacon casserole on Taming Twins): Mon = potatoes and veg; Wed = mash topping, under the grill, with baked beans; Fri = jacket potato.
Saves the boredom of 1 meal 3 nights in a row.
Reducing washing by hanging things out on the line/ by a wide open window or door after a wear to freshen them up. Some clothes are spot-washed in the sink with small amount of non-bio (eg if otherwise clean but got a spot of food on). We have cut an average of 1-2 loads per week.
Petrol: some people can't reduce their mileage but there might still be savings in the way you drive. Smoother driving, making sure there isn't excess weight in the car (crap in the boot). If you are always stuck in traffic, are there any journeys that can have the timing tweaked? Sometimes 15 minutes can make the difference between constant stop/start or coasting at 30.
I bought a Sainsburys midweek delivery slot for £40 for 12 months. Delivery Tues-Thurs. That's 77p for delivery each week which is definitely cheaper than the petrol/wear and tear on my car. It's also then easier to base my meal plan around what's on offer rather than doing a meal plan, getting to the store and overspending because something I didn't plan to buy is discounted.