14 day isolation and supermarket deliveries?

[Frangipanini]

I'm confused about this. If someone in your family wakes up with a temp then you all have to isolate for 14 days unless you live on your own and it is 7 days. OK, get that.

What about food? I've read on here that food delivery slots from the big chains are all booked up for weeks. So how exactly are you meant to get food, if you don't want fast food delivered, if you haven't prepped like a demon?

We are self isolating for 12 wks, whole household, as I have an autoimmune condition. We have deliveries booked, time will tell how successful they will be.