In the spirit of helpfulness, I'll give it a go:
Everybody in the UK who wants a vaccination will have had one by late summer and it's quite likely that, by then, there will be a programme ongoing of giving people differently formulated booster shots to protect against new variants. (Likelihood: 90%)
Domestically, England will be largely open (likelihood 75%) but many events and activities will be open only to those who have either been vaccinated or tested negative withing the last xx hours (likelihood 50%)
There will be strict entrance requirements to the country, with negative tests and quarantine, in some form or other, even for those who have been vaccinated, to guard against the import of variant strains (likelihood 33%).