No it's insane. Because you know viruses do one thing: they mutate.

Also heard immunity takes to long at which point all old people will get potentially infected too.

Also cases to death ratio (and infection to death ratio) are still on a magnitude larger then with the flu. Especially given that somewhat between 10-20% of infected need intensive medical care, all roughly at the same time if you don't slow the spread which likely can't be provided if that should happen increasing death ratio.

With such a strategy we at looking a mostly likely at >350000 deaths. Not unlikely even over 1800000...[]

Through well there is always very, very small chance that it will work. Less because it's a good strategy but because even if you do nothing there is a very very very small change for a virus to "self destruct" (not correct way to describe they effect but it basically similar to a self destruction to a outside observer knowing nothing about virology).

But gambling hundred of thousand lives one it would be insane.

Well except if you have no morals and want to destabilize the country. Through I don't think that's the case, incompetence is more likely.

EDIT: spelling

EDIT: Numbers based on not unlikely infection rate of 60% of population and IDR of 1% (health system not overloaded) and 5% (health system overloaded to some degree).

EDIT: argument based on heard immunity idea not explicitly the UK strategy