I may make a little bit but think I'm going to struggle, battery is already low (57%) so probably only just going to have enough to discharge for the hour and then will be using grid electricity after, which will be pricey-ish as I'm on Agile (luckily I will be out tonight, so should be low usage), not worth charging the battery beforehand because Agile price is already close to the saving session price!
Ironically, think my GF with no battery will do better, as usually would be cooking and running electric heating at the the session time, but she also will be out, so should be a pretty decent saving!