Inevitably things are never black and white. If we have a complete and total lockdown then people would be unable to buy food because the food factories and distribution networks would be shut. And what about if your car breaks down and you are a doctor unable to get to work because no-one can get the parts needed to fix it? And the old lady whose central heating broke and had no hot water because there are no replacement pumps?
That said, I think in trying to get right the balance between preventing as many deaths as possible, and on the other hand keeping things running as much as they can, they have consistently erred much too far towards the latter. And some of the decisions like not cancelling Cheltenham for example are inexcusable.
This "exercise once per day" is horseshit as well. People will abuse it greatly.
The other thing they have not done and which needs to be done because it is a HUGE problem, is there are no online delivery slots for most people. So people are forced to go to the supermarket and fight amongst the crowds with people staying nowhere near 2m apart and few wearing masks. This is a breeding ground for infection which will impact upon many.
The government should act immediately to help in any way it can to improve availability of delivery services - e.g. getting the army to do some - and also require the supermarkets to control numbers and safe distances.