I recently switched to Igloo Energy (from Utility Warehouse) for one reason, they were the cheapest supplier I could find with good reviews.
Switching was easy, I was able to get an accurate quote using one of my old bills and then all it took was 5 minutes on their website. Igloo then look after everything else.
I also used a referral code which gave me a £50 credit.
Here is my referral code, please use this link to get your quote, and then if you sign up with it you will also get a £50 credit that you can put towards your energy.