Just in case people haven't seen it - cafcass have issued guidance. Although it's not law, if parents follow it the courts should back them up. Crucially, it says follow government advice re self-isolation. It gives tips on what to do if a parent isn't having face-to-face contact because of this, and suggests making up the time when self-isolation is over.
www.cafcass.gov.uk/grown-ups/parents-and-carers/covid-19-guidance-for-children-and-families/. Click on where it says "please click here for advice". It then downloads a pdf document.