From the 14th January the travel restrictions to France are easing.
Fully vaccinated travellers from the UK will be allowed to enter France if they have followed the necessary entry requirements (https://www.gov.uk/foreign-travel-advice/france/entry-requirements)
Non fully vaccinated travellers will need to self isolate for 10 days.
The same measures applied to vaccinated adults are applied to any minors who are travelling with them, whether vaccinated or not.