Most homes built after 1935 will have cavity walls which could be insulated to reduce your heat loss by up to 35%. Subject to survey and grant funding you may be able to get this work installed free of charge by Enact Energy, simply call free on 0800 093 4050 for more details.
The video below from the Energy Saving Trust gives a good background on cavity wall insulation as well as ways to identify if your home has solid or cavity walls.
