Energy Helpline uses a calculator approved by Energywatch (the UK gas & electricity supply watchdog) and is completely free and straightforward to use. There's no hidden costs or surcharges. See if you can make a saving by following the simple instructions.
If you do choose to switch your supplier just take a few minutes complete the simple online form. There's no need to fill out any paper forms or sign contracts as you can do this all online. They then send off your details to your new supplier and then inform your old supplier. You don't need to do anything more. Easy!