Keeping your house warm can be costly but you can also have some ways so you can be able to reduce your expenses. One of them is that you may have positioned your sofa in the wrong place blocking out warm air that comes from your radiator. If your sofa absorbs the heat, it cannot circulate so better move things that could block the heat like curtains. Another way is to let the heat reflect from the walls by installing radiator panels. They are cheap and can be installed easily. They will prevent heat being absorb by the walls so the room can be warmed.
You can also use tin foils in places where heat could escape from your radiator. If your radiator is attached in your external wall, heat can escape. You can use tin foils placed behind your radiator so that heat would not be lost in the walls but goes into the room. Having thick curtains during the winter can also help in containing heat so they will not be lost. It is better is curtains have thermal linings. If you want to do it, you can use cheap fleece to line them. Another cheap way is to let the sunlight in during the day and close the curtains when dusk falls.
One of the ways to stay hot is to have some fire but the heat could escape from the chimney. You can use a chimney balloon or the insulators made of wool for your chimney to prevent heat from escaping. It is better also that you close the rooms that no one uses so that cold air would not interfere with the room you heated. You can also cover your floors so they would not consume the heat loss. You can use rugs and carpet.