It's not a stupid question. I reckon we could get quite near it, if people were willing to be selfless, and have a really strict lockdown. People could be given notice, so they could plan food, part of the arms budget could be diverted to pay for food delivery, and just the emergency and health care in operation, and with precautions
And whilst you eat your 3 weeks' worth of food supplies provided by the government for free, who is manufacturing, packing and shipping all the food you will need to buy once we're out of this 3 week lockdown? It takes weeks for food to reach a supermarket.
Who is keeping the gas and oil industries up and running, so you can have electricity, heating, and all that food can get to your local supermarket, in time for your return to the streets in 3 weeks' time?
Who's taking single mothers who don't drive to the hospital, to give birth? People who have a stroke or die in their sleep, how are these people taken to hospital or the morgue when they don't have cars?
How are people paying their rent and (increased) bills during those 3 weeks, if they can't work from home?
I'm not an essential worker but my job can only be done in person. If the business isn't open we don't get paid. If I don't get paid I can't afford rent or bills. Is the army also going to give me vouchers for rent and the water bill? Me and the millions of people in the UK who work in this industry?
It's a lovely idea. Completely unrealistic.