My feeling is that schools do have to re-open at some stage. Teachers have tried hard with online learning, but it can't replace the classroom. Some children don't have computer facilities at home or parents who are willing/able to organise them. There is no doubt that the most vulnerable children are losing out even more than they usually do.
However …
The UK still hasn't got a grip on new infections. Lockdown has been half-hearted and should continue and be even stricter and better enforced. It takes about two or three weeks for the results of lockdown to show up in the number of serious cases and deaths. Stricter lockdown would bring the number of infections right down, whereas loosening it now will result in the numbers spiralling out of control again and no chance of containment. There will be no alternative other than so-called herd immunity
Meanwhile, the government needs to get PPI made. For school staff, that wouldn't involve full gowns, but we need masks and hundreds of thousands of hand sanitiser dispensers.
Efficient test, track and isolate systems need to be in place, so that localised outbreaks could be stamped on. That involves having real boots on the ground, not just relying on an app. Recruitment for the "real boots" hasn't even started.
Nobody knows for sure how much children transmit infection, but it would be wise to err on the side of caution. The government didn't work with the teaching unions on this, but railroaded them and attempts to demonise them have appeared in the media (wonder who briefed them … ahem).
Rather than thinking from a business perspective (ie which children need most childcare to enable parents back to work), this should have been approached from a pragmatic and educational angle. It would, for example, be easier to manage if slightly older children (Year 2?) went back first plus Year 10 and Year 12, who will be sitting exams next year.
The first priority in schools must be an independent risk assessment of each school and the provision of resources. In China, for example, each school has a nurse, who is able to assess any child with a cough or sneezing.