More than half of England is now under tougher coronavirus restrictions after the severest measures came into force in Lancashire on Saturday, while Londoners are now banned from meeting other households indoors.
Here, the PA news agency looks at how restrictions differ across the UK.
A new three-tier system of coronavirus restrictions began on Wednesday.
Nationwide restrictions apply in Tier 1, which mean people can meet in a group of up to six people from multiple households either indoors or outdoors. Unlike in Scotland and Wales, the six includes children.
Pubs, bars and restaurants must close at 10pm and face coverings must be worn while shopping, on public transport and in other indoor areas.
Under the Tier 2 restrictions, people cannot meet with anyone they do not live with indoors unless they are part of a support bubble, while the rule of six applies for socialising outside.
Areas in Tier 2 currently include Greater Manchester, Cheshire, Derbyshire, West Yorkshire, South Yorkshire, Durham, Northumberland, Tyne and Wear, Tees Valley, West Midlands, Leicestershire and Nottinghamshire.
London, Essex, Elmbridge, Barrow-in-Furness, York, North East Derbyshire, Chesterfield and Erewash moved into Tier 2 on Saturday – meaning 25.2 million people will be in high-risk areas.
The most severe level of restrictions, Tier 3, means people cannot socialise with anyone outside their household in any indoor and many outdoor settings. Pubs and bars will be forced to close unless they can operate as a restaurant.
Weddings and funerals will be allowed to take place with restrictions on the number of guests, but wedding receptions are banned.
Lancashire and the Liverpool City Region are the only two areas of England under Tier 3 restrictions, meaning 3.1 million people are living under the toughest measures.
A tiering system is set to be introduced in Scotland, subject to the approval of Holyrood, replacing temporary coronavirus restrictions in place across the country.
It will indicate which level of regulations apply when the temporary restrictions end on October 25.
First Minister Nicola Sturgeon said the new framework will “strengthen our resilience to live with this virus” and will detail support for businesses in the future should they be the subject of further restrictions.
Pubs, bars, restaurants and cafes outside central Scotland can only conduct indoor business between 6am and 6pm and not serve alcohol, although alcoholic drinks can be served until 10pm in outdoor areas.
Pubs and licensed restaurants in five health board areas – Greater Glasgow and Clyde, Lanarkshire, Ayrshire and Arran, Lothian, and Forth Valley – have been forced to close for all but takeaway service until October 26.
Snooker and pool halls, indoor bowling, casinos and bingo halls have also been made to close and no outdoor live events are allowed in these five areas.
In terms of seeing friends and family, people cannot meet others from another household in indoor household settings across Scotland unless they are part of an “extended household”, available to people who live alone or only with children under 18.
People can meet outdoors in groups of up to six, not including children under 12, from no more than two households, and a maximum of six people from two households can meet in indoor hospitality settings, such as pubs and cafes.
Ms Sturgeon has also advised Scots against travelling to high-risk areas of England, singling out Blackpool as “associated with a large and growing number of Covid cases in Scotland”.
First Minister Mark Drakeford has said the Welsh Government will be meeting over the weekend to discuss a circuit-breaker lockdown and will announce any decisions on Monday.
People in Tier 2 or 3 areas in England, as well as the central belt of Scotland and the whole of Northern Ireland, were banned from entering Wales from 6pm on Friday.
Currently, there are tighter restrictions in 17 areas of Wales, including Cardiff, Swansea and parts of North Wales, affecting more than 2.3 million people.
These prohibit people from entering or leaving their local area without a reasonable excuse such as work or education.
Under the more general lockdown rules in Wales, licensed premises have to stop selling alcohol at 10pm, face coverings are mandatory in indoor public spaces and public transport, and people cannot gather in groups of more than 30 outdoors.
The rules also say people are not allowed to meet indoors with people they do not live with, unless they have formed an extended household.
In areas with no local restrictions, up to four households are able to join to form an extended household, and can meet indoors in a group of up to six people, with children under 11 not included in the number.
– Northern Ireland
Tighter coronavirus restrictions announced by Stormont First Minister Arlene Foster came into force in Northern Ireland on Friday.
Pubs and restaurants have been closed for four weeks, with the exception of takeaways and deliveries, while schools will close on Monday for two weeks – one of which will cover the half-term Halloween break.
Under the new restrictions, retail outlets will remain open, as will gyms for individual training.
Churches will also remain open and it is understood a 25-person limit will be placed on funerals and weddings, but wedding receptions are prohibited.
People should work from home unless unable to do so, and are urged not to take unnecessary journeys.