Sweden based their plans on the premise that Swedes would do what the government told them to without much complaint and that social distancing could be maintained that way.Sweden didn't overwhelm their hospitals either, with simple social distancing, hand washing, and other light-touch measures.
Same goes for the Motherland (Japan).
Britain based their plans that after a few months the British would kick up a fuss, bitch, complain, and eventually a minority would stop obeying social distancing measures.
And I think I see a bit of a problem with the idea of Britain trying to follow the Swedish model. The first thing you would have to do to implement the Swedish model in Britain is to somehow replace all the British with Swedes.