You may have seen last Friday afternoon's government announcement that the self-isolation period is being reduced from 14 days to 10. The change comes into effect today.

https://www.gov.uk/government/news/uk-chief-medical-officers-statement-on-the-self-isolation-period-11-december-2020#:~:text=A%20change%20to%20the%20self,10%20days%20has%20been%20announced.&text=This%20change%20will%20apply%20in,breaks%20the%20chains%20of%20transmission

We have received confirmation from Portsmouth's Deputy Director for Education that this applies to those who are already self-isolating; in effect, the self-isolation period can be reduced by four days.

https://springfield.uk.net/images/files/correspondence/recent/Letter_to_All_Parent_re_Isolation_Period_dated_141220.pdf