Some observations on the test and trace system from personal experience.
Background - our family (me, Mrs W, daughters W1 (15) and W2 (13)) are taking part in the ONS study. This involves weekly PCR swab testing for 5 weeks then monthly for a year.
On 16 Dec W2 tested positive (we got the results on the 21st) so the family went into isolation. She only had mild cold symptoms - we certainly wouldn't have gone for a test off the back of them. W1 then developed the same cold symptoms so we got her a postal test on the 24th and Mrs W the same so she went for a walk-in test on 27th - both were positive. I stayed symptom free and we all had the ONS weekly test on the 29th which found that W2 was now negative and the rest of us positive.
The testing regime has been pretty efficient and of course we are lucky to be on the ONS study - without that we wouldn't have gone for tests as none of us have had classic Covid symptoms.
The trace bit has been less good; there are two main problems:
1. It is set up on the basis that you are the first to be positive in your household. You are required to give details of people you have been in contact with and they are required to isolate for the relevant period. The problem comes when you have had it and gone through your isolation period and have no further symptoms. The guidance is clear that you are no longer required to isolate even if someone else in your household tests positive. However if they do, they are required to give your name and details and you then get further texts/emails telling you to self-isolate, which is incorrect.
2. It does not handle children well. I had to deal with the NHS when W1 was positive because she is under 16 (Mrs W did W2). That's all fine. However, I had to give my mobile number, and then received texts telling me to self-isolate rather than her. This is a known bug and I was told to ignore them by the NHS person i.e. they related to her not to me. Not ideal. Worse, when I subsequently tested positive and received another text saying 'you have recently tested positive and need to self-isolate' I assumed it was for her not me (I did get a call later that day which cleared up the confusion).
Finally, I still haven't received the code from the NHS to put into the tracker app to alert people that I might have come into contact with. I assume this is due to the system being overwhelmed and struggling to cope with numbers rather than the systemic problems above.