Looking for the cheapest energy supplier for our new house.

Here is a link to a calculator and information from a USwitch survey. I hope it may help you
http://www.simplyswitch.com/energy-consumption.html

Whatever supplier(s) the property is now connected to, making a decision now with its uncertainties about companies revising their tariffs in the near future, is not necessarily the best thing to do- see http://forums.moneysavingexpert.com/showthread.html?t=234243
on this forum. The advice is to wait. Another thing to look out for is a special charge for gas if the property is not Transco connected. I do not think the sites like USwitch include this element.

This is my opinion only but TBH you need to be patient until the present round of increases is out of the way, and, in fact, until you have a year’s consumption figures- at minimum a winter and a summer quarter- to hand.