Face coverings will become compulsory on public transport and in shops. Not including hospitality.

All international arrivals entering England must take a day 2 PCR test and self-isolate until they receive a negative result.

All contacts of suspected Omicron cases must self-isolate for 10 days, regardless of their vaccination status. They will be contacted by NHS Test and Trace.

https://www.gov.uk/government/news/prime-minister-sets-out-new-measures-as-omicron-variant-identified-in-uk-27-november-2021