Heat the room, not the walls.
Walls can absorb a lot of heat energy, use some foil insulation (or 3-5 layers of tin foil) to reflect the heat energy back into the room
Cover up your cracks
Draughts or gaps around doors and windows will allow heat to escape, use insulating tape to cover up small gaps and cracks, make sure you apply the tape tightly. A draught excluder for behind the door is a great investment too.
Make sure your radiators are heating correctly. If they aren’t heating to the top you will need to bleed them (releasing trapped air ) Using a radiator bleed key, open the radiator, the valve is usually at the top, then when the hissing noise goes, close it tight.
Cover the pipes.
Insulating the pipes in your home can keep the water inside them warmer for longer, don’t forget to insulate any water pipes outside your home, this can stop them rupturing during very cold/freezing weather.
Windows allow a lot of heat to escape. To keep the warmth inside the home, invest in some heavy curtains,they will stop heat escaping, but during the day keep curtains open, the sun will heat up the room.
Get the boiler serviced now. If its not up to scratch you could be burning money, or even worse, it could break down and leave you in the cold. Make sure to use a GAS Safe certified person.
These are just some options to help heat the home and be more efficient, for extra warmth,we have a range of heaters for hire which can also help to keep the house warm.