You are right that just turn to full auto mode, and let the camera take over.
Flash will pop up automatically, it will pre flash to auto focus, then you get the shoot!
I don't think your friends will wait for you to manual focus ... If really too dark, cannot see clearly also.
Just make sure it is not because you are too close to your friends. Just step back a bit.
I.e within Minimum focus distant of your lens.