Look up (or make up) a postcode using the postcode finder on
http://www.royalmail.com find a postcode
http://www.royalmail.com/portal/rm/postcodefinder?catId=400145&pageId=pcaf_pc_search&gear=postcode
I expect it will be the old Eastern Electricity (Eastern Region) which is now EDF. Bedfordshire is not an area I went to when I was there. Put in £10 a month Gas (if they do not have GCH) and £50 Electric and tick Economy 7. Search results by price. Look for Electricity only, then Both.
You will spot the prices from the incumbent supplier (the company that used to be the Regional Electricity Company) because they will have the highest prices (this is not a joke).
Looks to me like British Gas will be the cheapest for Electricity only, but this can change as more price cuts are announced. I use themn for my Electricity.
Atlantic Energy are cheap, as long as you are not in one of the regions of their parent company, which is Scottish Hydro, Southern Electric and SWALEC IIRC. I use then for my Gas. They rebate one month's payments every year as a discount.
Screen suppliers by Quality of Service (If you can, or have any industry knowledge) and avoid the bad ones, or you will get lots of incorrect bills; or double bills; or no bills for a long time, then a huge one. When you switch, take your own record of meter numbers and meter readings and check the bills to them.
Internet Only tariffs (no printed bills) are often cheaper. there is usually a discount for Direct Debit monthly payment.