I will try and make clear what I wrote up-thread. I believe the 'plan' (if there is actually one) is to try to balance the short term health hit with the longer term health and economy hit. If the Government shuts down the whole country then a number of problems arise. The economic damage would be huge, we would be delaying the inevitable as even if we self isolate, sooner or later we have to get out of isolation as I guess 2 weeks would be the maximum we could cope with, when we come out of isolation Bang! infection rates go up. In addition, if we isolate we potentially cause more problems, if the schools close, then Mummy and Daddy who should be at work in the NHS or care homes are now unable to come to work as they are looking after Jnr. If Mummy and Daddy have their parents around then perhaps Jnr goes to Grandma for a while. Grandma is just the person you don't want an infected kid around.
I think the plan is a wait and see approach to try not to have a big peak of cases so the NHS is overwhelmed, but also is not sat around doing nothing. It is simply trying to use the limited resources they have. The bonus is that economically that works best too.
However, I think that we are possibly beyond that control stage as the government needs to be able to predict and model weeks into the future and I guess their models are at the point of trying to put the brakes on the spread. Sooner rather than later we batten down the hatches.