It depends entirely where you live and I hope people will be sensible with regards to their particular circumstances.
I am the designated going out of the house person. The rest of them are staying put to minimise risk of passing on or getting CV.
I drive to the local shops, 2 mins in the car, as I live in a built up area close to a large park.
Since the lockdown, the pavements have been busier than usual with joggers, walkers, kids on bikes, babies in prams with more than one person with them, all heading to or from the park.
They are doing safe distancing once in the park, but not on the way to or from it. My foot journey to the shops would take me past 3 of the park entrances.
The roads are pretty much empty, so the chances of an accident are much lower and given it's a 20mph zone I would be looking at a fender bender at most. If the car were to break down (unlikely, given it's condition) I would pull in and be back at home in 5 mins on foot.