Back from Richmond Skoda, airbag error message was indeed a software issue and a recall has been issued. All resolved.
Methinks that a known defect that relates to an important safety issue Skoda would contact owners of cars likely to be affected rather than wait for warnings to appear on the instrument display and have drivers worrying about whether their cars were safe to drive or not. Had I known I would have taken the car over on my own, not dragged She Who Must Be Obeyed along in our other car in case the car was declared unsafe to drive!