I am so, so sorry that you're going through this - in a country that keeps banging on about being one of the richest in the world, apparently, this really shouldn't be happening. (I'm even more furious today after the rich morons in charge of the country closed ranks to protect that twonk Patterson, even if he has now resigned.)
I'm also one of those who's never voted Tory, and never will, and it infuriates me that their voters don't understand that situations like yours are what they're effectively voting for, or at the very least condoning.
I also grew up poor, and remember a childhood where my parents knew 100% recipes with potatoes - we ate a LOT of potatoes. And pastry. And starch in general. Plus cheap cuts of meat, mince etc. As I've got older I've learned how to bulk food out with rice, lentils, barley, and really understand what a great idea slow cookers are. We've recently invested in a small alternative called a Wonderbag, which uses the old haybox or Dutch oven principle (though of course you have to be able to buy it in the first place, though there are instructions on the Internet on how to make your own).
I don't have much to add otherwise, there are some brilliant tips on here. In terms of food with lots of calories, peanut butter (as long as there are no allergies, obviously) is one of the most calorie dense foods there is. I also see someone suggested cookbooks from the library, by far the best one I ever had (even though it's really old now) was the Cooking in a Bedsitter one, which had some brilliant suggestions.
I'd also recommend putting curtains (or fleece blankets, or anything you can get) up at windows, and doors, and rolling up towels to put against anywhere there's a draught. It's amazing what a difference it makes.
And yes, socks in bed! And I've even been known to wear a hat and a fleece zipped up to the neck if necessary. We don't have central heating in our flat, and I often wear a hood or a cowl or similar during the day. When I was a kid my parents used to put coats on the bed to help keep us warm - duvets were an unaffordable luxury when I was young. Also, we have a couple of old stone hot water bottles that we got at our local charity shop, like the ones we had when I was young - they come in various sizes, and they really do stay warm all night. Also, using flasks to store hot water, soup, etc, to keep your energy use to a minimum.
I really hope your social worker and the other organisations can help get you sorted. People who've never been through this kind of thing have no clue how exhausting it is, either.
