Turning your heating thermostat down by 1oC could cut your heating bills by up to 10%.  This can save approximately £50 a year in your heating bills for the average home.
If you do not have one of the modern hot water tanks, which already have, insulation already added you might want to consider fitting a thick insulating jacket for your hot water tank.  They are widely available and are very inexpensive and could pay for themselves in under a year.

Insulating your hot water pipes (where accessible) is a simple project that can save money in heating costs.  Its best to start with the pipes that go from your boiler to the hot water tank as these will give you the biggest benefit as well as making your home cooler in the summer.