I've asked my sources
and apparently long-term shortages are unlikely, however long-term price increases on food are very likely... because the problem is haulage. Non-UK drivers don't want to come to the UK but will do so if offered enough money, thus, haulage prices have basically doubled.
And the main reason is general Brexit/Covid stuff not the pingdemic... it's being scapegoated. This is Brexit, and this is forever. Put aside an extra £50 a week for your food shopping because prices are going to be permanently hiked at some point.