I would say, its pretty much always going to be cheaper to make your own food from scratch. Soup is dirt cheap, and you can put pretty much anything in it, cheapest rice I've found is Tesco Value Long grain rice, 1KG for 49p. Lentils are also a cheap source of protein, but i tend to find dall a little bland on its own. Potato curry with finely chopped onions, 2 tins of chopped tomatoes, ~4 teaspoons turmeric, 6 birdseyes, ~2teaspoons ground coriander, ~2 teaspoons cumin, couple of black cardamoms, 3/4 cloves of garlic, maybe some whole cloves, and some chilli powder to taste is a good starting point. After you make a couple of curries from one region you'll get an idea about how much to put in and what to put in, and be able to make it up as you go along. We discovered that if you want the curries to end up like they do in curry houses, fry your onions in lots of ghee, chop your onions really really fine (as fine as you'd chop your garlic almost), and cook for ages. We also found we needed to double all the spices in the given curry recipes.
If you are making curry or chinese etc., go to a chinese/indian supermarket - there will be one in the centre of the city, and the spices etc. will be hugely much cheaper. For example I bought a litre of soy sauce for the same price as 100ml in tesco, and my kilo of turmeric came in at £4.50 a kilo as opposed to tesco's £18 a kilo if you buy the little 45g pots.
You'll also be able to eat much better if you cook and split the costs between a group of you. My flatmates and I do this, and the week when one of us was away, it cost us pretty much the same as it usually does, hence cooking for 3 costs about the same as cooking for 2. Plus you wont have to cook every night.
Never buy take-away unless its special occasion. It is obscenely expensive. At the very least, if you aren't cooking from scratch try super-market ready meals first. It's all equally unhealthy. For instance, Domino's XL Pizza is £8.00, I could instead buy 4 Tesco Pepperoni extra thin poiza's at £1.75 each. No way Domino's is coming out of this better off.