That is my understanding too. I've read through a lot of the official publications[0] and nowhere found reference to "herd immunity". The best reference to "herd immunity" I've been able to find is the quote from the UK's Chief Scientific Advisor Patrick Vallance that "our aim is to try to reduce the peak, broaden the peak, not suppress it completely; also, because the vast majority of people get a mild illness, to build up some kind of herd immunity so more people are immune to this disease and we reduce the transmission, at the same time we protect those who are most vulnerable to it."[1] but this still seems clear that the main aim is to "broaden the peak" and get the benefits from buying more time that this brings, possibly including the "herd immunity" point (but not limited to it - there will be other benefits, e.g. more time to find a vaccine).

What isn't clear to me is what the exit plan is for the countries that have a full lockdown in place at the moment. Are they going to keep lockdown in place indefinitely and hope a vaccine is found? Or are they going to lift the lockdown and then repeat when the virus begins spreading again?

[0] e.g. https://www.gov.uk/government/publications/coronavirus-actio...

[1] https://www.ft.com/content/38a81588-6508-11ea-b3f3-fe4680ea6...