Do my kids need to islolate in this situation?

[52andblue]

Hi, silly qu possibly but

My kids visit their father whom I'm separated from most weekends.
They are there now, When I dropped them off I went had a cuppa.
He just texted that he has a temperature and thinks his sense of smell is a bit off but no cough so far. I suggested he get a test.
Do the kids need to stay off school until he gets the results, even though they don't live with him?

Strictly speaking no. This is copied from government website.

Self-isolate immediately if:

• you have any symptoms of coronavirus (a high temperature, a new, continuous cough or a loss or change to your sense of smell or taste)
• you've tested positive for coronavirus – this means you have coronavirus
• you live with someone who has symptoms or tested positive
• someone in your support bubble has symptoms or tested positive
• you're told to self-isolate by NHS Test and Trace or the NHS COVID-19 app
• you arrive in the UK from a country with a high coronavirus risk – see GOV.UK: how to self-isolate when you travel to the UK

But if they were effectively living as a household over the weekend (no social distancing etc) then they probably should. I don't think you need to though, not unless they have symptoms.

OK, if you share custody the rules are different. Do you share custody?

Not shared custody, no.
No SD between H and kids over weekend.
Not proper SD between me and exH for over 15mins.
Gah!
Isolate until clear test it is, I reckon!