So it looks like the feature you call Auto Brake is called Auto Hold on my version (Thai MG4 X) and has to be enabled via the Safety tab in the Vehicle menu although luckily it's one of the few settings that the car remembers overnight. A firm press on the brake pedal at rest then sets the brake until you use the throttle again. I just went out to check where the "A" might appear and. wouldn't you know, AutoHold refused to turn on. I tried every combination of brake pedal, handbrake and gear selector and still no joy. A trip to the dealer looms...
Love the fancy pedals,by way