There are some smaller changes you can make which will also result in energy savings and an improved BER.
Replace or seal old windows
Single-glazed windows tend to be lose a lot of heat. In many cases, draught-stripping will improve this but secondary glazing or complete window replacement can return highest overall savings.
Choose low energy lighting
Replace old inefficient bulbs with low-energy light bulbs for a noticeable improvement in electricity bills.
Check your ventilation
Try to reduce draughts and install a chimney balloon in your fireplace when it’s not in use to keep heat in. Older vents may need replacing to encourage better airflow.
Get a lagging jacket
A thick lagging jacket for your hot water cylinder will keep your water warmer for longer, improving your BER and saving you money.