From available evidence, the logistics of getting effective herd immunity suggest herd immunity will be unlikely. We don’t know enough about the virus, the vaccine, the duration of immunity from the vaccine or from having been infected, or the percentage required for herd immunity (in some diseases requires about 95%).
Even if there were zero cases in there U.K. after mass vaccination, there will be some that have refused or slipped through the grid, and also legal or illegal immigrants and visitors arriving from overseas, including countries poor standards. Then there may be new strains developing not covered by the vaccine or previous exposure.
In many years to come, perhaps, perhaps, it could be one of those diseases that you only need inoculation for if travelling to certain misbegotten countries. Just now we don’t know.
If a definitive cure were to be developed, that might alter the scenario. If detection and treatment became easier and cheaper than multiple vaccines then risk taking would cease to be a big deal, especially if long term as well as short term complications could permanently be treated. But that is also a big “if”. I read that the highest risk group for the current vaccine is pregnant women, being advised not to take it until a little more is known. For anyone else, it seems to me utterly reckless to refuse having it when offered.
At some point, there may even be a choice of vaccines. But not yet. Given that most people will not be offered it immediately, you might well consider yourself fortunate when you do get offered it, not only potentially to save your own life but to allow you to walk around without accidentally killing someone else when you would only know after that happened, if it did, that you could have avoided doing so.