Hi Dr dr,
Got my mate to work out the prices at the momonet and on a single rate meter using 29018 is about £3300 and to break even using E10 you would need to use at less 40% on the off peak to break even with the peak rate. Thats based on MPAN 12 prices as you said you where London. Also EDF lost their license to install E10 and all their fancy tariffs since they lost the I think there SWEB and or SEEB license and everything migrated to the LOND license everything fell through then. The reason I know this is a customer who wanted warmwise install like he had in his old property couldnt in his new because they couldnt fit it as never had license to bill (CRAZY). Please let me know what MPAN area you are in and I will try to do more digging for you to see if their will be a more appropirate tariff that E10.
Kind Regards
Mr MPAN