As far as I can tell the Swedish government never had this plan. It was mentioned in an interview and dismissed as unworkable, journalists misunderstood.
On the other hand the UK government appears to have had no plans whatever until jolted into action by the fear that public opinion would turn against them.
What Sweden has done is similar to Norway, where I live, which relies largely on voluntary changes in behaviour and temporary closure of institutions and businesses that require close contact between employees and customers. But Sweden took longer to implement those measures and also Swedish society is different from Norway, anecdotally Swedes seem to me to be more urban people than Norwegians and more gregarious.
Exactly why Sweden has a much higher death rate, 36/100k inhabitants versus 4.3/100k in Norway, is unclear at the moment partly because of different definitions but also because of differing conditions, and the epidemic being at different stages in the two countries.