From 2nd December, childcare bubbles are allowed in all tiers. A childcare bubble is where one household links with one other household to provide informal childcare to a child or children under 14. All adults in both households must agree to this arrangement.
From 2nd December you may change your childcare bubble provided that: at least one person in the proposed new childcare bubble is under the age of 14; and neither household is part of a separate childcare bubble which they intend to remain a part of.
If you decide to change your childcare bubble, you should treat your previous bubble as a separate household for 14 days before forming a new bubble. This means following the rules on meeting people from other households in the tier you are in.
The Government has also updated guidance on how you can make a support bubble with another household and safely expand the group of people you have close contact with during the coronavirus pandemic. This also includes information on how to switch your support bubble. Links to this information are below.
Guidance:
https://www.gov.uk/guidance/making-a-childcare-bubble-with-another-household
https://www.gov.uk/guidance/making-a-support-bubble-with-another-household
https://www.gov.uk/guidance/local-restriction-tiers-what-you-need-to-know