When the supply chain was disrupted for "just" a couple of days during that Beast from the East this March, there were empty shelves due to the lorries not being able to get through. Not panic buying - just no re-stocking 
We genuinely had no bread and ended up having to buy an expensive (and stale
) "artisan" loaf at the local deli (nothing in the Sainsbury's Local), having walked to the shops (roads were impassible, even in inner city Glasgow
) (unfortunately my sourdough starter was dormant at the time and would've taken 36 hours to get going again - which I did do especially after paying an extortionate amount for a loaf that wasn't nearly as good
).
We got the second last milk in the shop - no more than we needed.
We ate well despite/because of that as we were fortunate enough to have a well stocked freezer and cupboards.
I intend to continue to be prepared - but with the addition of extra supplies of my daily contact lenses, which come from Ireland. I usually only order more the week before and I really don't like wearing glasses.