It's happened to me too. Two or three times I've found myself in what appears to be absolute darkness when trying to dim the headlights.
I find the auto-dipping to be a pain because the bloody car is always dipping them when there is no approaching traffic - usually at a difficult bend, when it sees its own lights reflected in the warning sign. It also dips the lights if it sees tail-lights ahead, even if they're more than half a mile away. I usually over-ride the auto-dipping, then I have to be careful.
There are two ways. Maybe the best one is to pull the stalk towards you to dip the lights, then again to go back to full beam. This doesn't risk going anywhere near the other controls. I find it awkward though, because the stalk is designed for people with larger hands than I have, and the reach is a bit long for my fingers. I have therefore adopted the second way, which is to push the stalk away from me with the flat of my fingers, taking care only to touch the smooth part of the stalk nearer the steering wheel column. Again this avoids interfering with the auto-light switches.
If you switch off the auto-lights you WILL forget about it, you WILL leave the car parked with the headlights on, and you WILL flatten the 12v, I suspect. (Or maybe you won't, if the car tops up from the traction battery. What do I know?)