I think Watapalava raises an important issue.
The problem with contacts of omicron cases, or suspected omicron cases, having to isolate is that it re-opens the issue of malicious or misguided reporting of 'close' contacts.
You may think that the brief conversation you had across the roof of a car with another parent doesn't make you a close contact, but the other parent might. You might think that your cleaner being in your house for four hours with the windows open while you were out and you didn't return for hours doesn't make you a close contact, but your cleaner may not agree. Or you may think someone at a social event seems a bit under the weather and take care to stay the other side of a well-ventilated room from him, but he still names you as a close contact to T&T.
Then there are people like the guy who heard that his ex was remarrying and named her as a close contact just before her wedding although they hadn't seen each other for years.
There is no appeal. If T&T deem you a close contact of, these days, an omicron case, you must isolate no matter how much you disagree you were a contact, or risk a £10,000 fine.
And if the point of isolation is to prevent spread, surely if I tell the people I have been in contact with as soon as I get my result, if they agree that we were contacts they will be able to isolate much sooner than if they don't hear until I've given their details to T&T and have been called. And people who aren't going to isolate, or even those who will mostly isolate but maybe do a quick trip to the shop, will do that regardless of whether it was a friend or T&T who told them to. But if they heard from T&T they are more likely to leave the phone at home.