Can someone please help me out with Self Isolation dates

[EffoffDelta]

Name changed for this. I took DC to an outdoors event last Thursday and they were joined by their best friend and their mum. Yesterday dc's friend woke up with a high temperature and a cough and as far as I am aware they didn't have any symptoms before but I am not sure. I dont know if they will take a pcr test but I am guessing that they will. If friend tests positive for covid how many days are we likely to have to isolate as in when would our isolation period end? (This would make a good SATS exam question! 🤔).

Please can someone who knows advise me. Thank you

Thank you all for replying. @AlmostSummer21 I seemed to remember something about 5 days as well, and didn't realise that T&T only contacted those who had been in contact within 48 hours of symptoms starting. I somehow had it in my head that it was all contacts within the last week since symptoms started (5 to 7 days) . I am so relieved and have danced my happy dance 💃