what's likely to happen in England after lockdown/tiers are eased at Christmas can be pretty much estimated based on the Welsh experience.
Firebreak = showed positive results.
Release = virus starts spreading again = more restrictions
https://www.walesonline.co.uk/news/wales-news/coronavirus-wales-mark-drakeford-christmas-19355104
it's a virus, and it will spread. it will keep spreading until it runs out of victims to infect. people will meet up, even if only in the legally sanctioned arenas of essential shops, the workplace, schools, colleges and transport, and it only takes a second's inattention with an unsanitised hand to face, mask, door handle, etc.
if the government policy is intended to mark time until a vaccine is available, then lockdowns and other restrictions will be with us for a good while yet. they are not going to eliminate the virus - only a 100% curfew for weeks will accomplish that.