Bulb are currently offering £50 free for switching to them for your gas & electricity using this promotional link. They already have a great reputation as the cheapest supplier in the UK; I've been with them for a couple of years now and I've saved a fair bit. You don't need to contact your old supplier to switch. Just complete the form on Bulb's website and they take care of everything for you. It takes minutes. Give me a shout if you have any queries. This is UK only, btw.