For anyone actually able to get out for the shopping - try the smaller supermarkets if there are any near you, rather than the huge supermarkets.
We do our weekly shop at a large Waitrose (hardly any queue late Tuesday mornings so far) but sometimes use a nearby small Sainsbury - got flour, Easter cards, stewing steak, minced meat, eggs there this morning. Freezers looked quite full too although I wasn't looking for frozen stuff so don't know what was in them.
We also use our local BP garage (M&S foods) occasionally if we run out of milk - they always seem to have eggs, bread, milk and some fresh meat and veg. We call in there if necessary on our daily walk - always quiet there too now, with so few people buying petrol. It's also the only place that sells food within three miles of us.