We HAVE to get rid of the herd immunity thesis - see my last post about deaths.
I dont know which Oxford University model you are referring to but the truth is that without testing we simply dont have a clue as to the proportion of the population which is infected. It is more than the current 43,454 but it is unlikely to rise above 10% of the population during lockdown. Full herd immunity is 40 to 70% of the population. So any attempt to use herd immunity / partial lockdown etc condemns an additional 30 to 60% to infection. ie 20 to 40 million with perhaps an additional 200,000 to 4,000,000 additional deaths.
Given lockdown is supposed to limit deaths to 20,000 and to avert 500,000 deaths (Imperial modelling) there is absolutely no benefit in 3 months lockdown and economic destruction if you are then planning herd immunity. So please lets put this suggestion to bed.