As for the other stuff you mentioned, its certainly true that the government have been guilty of mixed messages, unsustainable claims, contradictions and sometimes leaving large holes in the picture they paint.
Supine already did a good job of puncturing the overly simplistic binary thinking about vaccines. Its not a question of the vaccines totally eliminating transmission, but rather reducing it, to give just one example.
I can agree with you in so much as the government have deliberately not come cleam about all the implications of the Delta variant. They dont want to cross such bridges unless they have to, and will leave such things as late as possible. So far with Delta they were forced to acknowledge some its implications when they delayed 'freedom day'. But other ramifications have been pushed further out and will only make their presence felt if deemed necessary by circumstances in autumn or winter. And then they will acknowledge such things as part of a sales pitch to renew legislation, impose new restrictions etc.
There was also a problem involving the public being oversold a grotesquely oversimplified version of herd immunity and the benefits of vacination, how much pandemic weight vaccines could reasonably be expected to carry on their own. Only a further test of time including seasons like autumn and winter will really inform everyone about quite what to expect from the new normal. A range of possibilities exist, which is why exact predictions about what will happen next are limited so far. The government have pushed ahead more quickly than it is sensible to do, but eventually they may reach the intended destination, just not as quickly as they have often claimed.
I would suggest that the government have tended to sit somewhere in between expert advisors and the right-wing press in regards these expectations, The likes of Whitty and Vallance were careful not to claim they expected sterilising immunity and total lack of transmission in the vaccine era. The right wing shits in the press preferred to paint a delusional picture of the new normal being the same as the old normal. The government have floated around in between, and are easily buffeted by circumstances, very much including the properties of new variants that emerge.
The government are not relying on vaccines alone. They are relying on a mix of vaccines and infections and public behaviour, with tougher back up options available for the worst moments. Its a numbers game and as time goes on they believe the changing susceptibility picture, both via vaccines and infections, gives them more wiggle room to get the numbers to add up (mostly hospital numbers). They do make a mess of it sometimes because of politics and because they want to have their cake and eat it. Their approach is not without risk given there are cycles of raised expectations followed by dashed hopes. They seem to prefer to lead people on a dance via those cycles to other approaches such as a more honest framing about behaviours we can get away with in summer but not winter, for example. The wheels would probably fall of that wagon of theirs if such cycles repeat indefinitely, so they are ultimately banking on the new normal eventually resembling the old normal to a greater extent than seems possible for the rest of 2021 and early 2022.