Annual Energy Calculator with which you can compare 2 tariffs one of which can be split or single rate, and it can accommodate different or the same gas prices on each tariff. Thus if you wanted to compare a single rate and an E7 tariff and they both had different gas prices or standing charges, you can do that.
What would you like to see that I may have missed? Here is a guide screenshot, and does anyone want to have a go at breaking it? If so I will provide a link by DM
It has stuff happening underneath, so this screenshot is only a guide.
All that is necessary is to enter your rates and standing charges and it will calculate all your costs (only including vat)