When can DS return to school?

[Hodl]

Hi
DS13 had a positive LFT so did a PCR home test on Tuesday and sent it back the same day. Now Friday, had no results back, just rang 119 and they had no trace of it?? So I've booked him in for a walk in test this morning.
How long does he need to be off school for, is it 10 days from the positive LFT? He still has a high temp, cough, sore throat etc.

He did another LFT yesterday and the positive line came up immediately, even before the control line (previous tests were a faint line but obvs positive.)

I think it’s 10 full days from a positive PCR, or onset of symptoms, whichever came first.

I'm in Scotland so can't guarantee its the same but here it is 10 days from symptoms or otherwise if symptomless 10 days from LFT

Thanks.
Ds's school is really strict on absences but I don't want to send him back until he's feeling better. He's been really brave so far!