Update: After performing the voltage drop test (which was difficult as the spike from 20ma to 4A only lasted 15 seconds at a time and then had to wait another couple minutes) fuse 37 was found to be the culprit (~6.5v which converts to bang on 4A).

This is the front heated seats circuit. Not sure which front seat is causing the issue - without removing the seats and fiddling with wires I have simply removed the fuse for now. Will be missing my heated seats as winter is coming!

Will check the battery level (full charged at 13v now) overnight and see how it goes. Found a similar thread here Battery Drain need VCDS garage to check alarm siren near Dawlish - Skoda Octavia Mk II (2004 - 2013) - BRISKODA if anyone is in a similar situation. Think the next move will be onto the stealers for a quote on fixing the heated seats.