So.
Thank goodness yesterday we took DDs out of school (had decided this at beginning of the week). And DH finished his last bit of on-site duties and is WFH from now. Yesterday also we received our "final" online supermarket delivery, in which hardly any of the store-cupboard items was available. So thank goodness we hadn't run down all of our Brexit stash and also we saw how things were going so have been gently restocking for over a month.
Some time yesterday PM I started a tickly throat and mild occasional cough. Today throat is a bit more tickly and I've been coughing slightly more frequently. No other symptoms or discomfort, could well be some random winter bug.
But I guess this means our household is going into self-isolation for 14 days.