A rough estimate would be around 30kWh but would it be 8 hours? If you plug in at 9pm and unplug at 8am, it’s 11 hours which should exceed 40kWh. You need to make sure all plugs, cables and sockets are more than capable of running at 12amps for 10+ hours at a time, loose connections will spark and be a huge problem, any unnecessary resistance in connections will generate heat and that can melt plugs to sockets before you know it’s a problem. I used a 15 amp outdoor extension lead with a good circuit breaker in a brand new wall socket and I was still renewing the lead every 18 months or so. I’m sure @kezo can recommend minimum specs for the electrics you need.
I'm Autistic, if I say something you find offensive, please let me know, I can guarantee it was unintentional.
I'll try to give my honest opinion but am always open to learning.
Mark