Have the dishwasher/washing machine/dryer finished by 8am or start after 9 p.m. to avoid peak use
Turn off all sockets and avoid leaving things on standby, such as t.v., dvd, pc/laptop
Turn off phone chargers when your phone is charged
Switch off lights not in use
Use kettle/hairdryer less often.  If boiling the kettle, only boil as much as you need.
Don't stay as long in the shower.  I sometimes set my mobile phone alarm to remind me to finish after 3 minutes.
Turn off outside door light when not needed.
Only boil the kettle for as much water as you need
If using the oven, try to bake/cook a few things at once
Use hoover less often
Use dryer balls in tumble dryer (or hang clothes outside to dry!)
Hoover under the fridge and around condenser coils as a build up of dust can increase electricity use
Defrost freezer every so often
Avoid putting hot food straight into the fridge.
De-scale kettle regularly (can use white vinegar to do this)

These tips came from a selection of Magicmum.com parents!  Thanks to everyone who contributed.