"Herd immunity" is only achieved by 80-85 % of the population being Vaccinated, or the old diseases now controlled, would have disappeared long before vaccines came on the scene.
Immunity cannot be passed on. Let that sink in. A small immunity may be passed on by a breast feeding mother, but this is not effective at protecting all, hence we sensibly vaccinate as many people as we can.
This virus has been found in people who have had the disease and recovered, and then tested positive again. They either did not build up any immunity, and were re-infected, or it lay dormant and came back, again no immunity.
The U.K Governments "policy" which is basically go home, stay two metres away from others, and if you can manage it die, that saves their Government money, is Totally Insane, and is the callous, calculated murder of more than likely many hundreds of thousands.
Do you really think this will work out well ?