Test and trace

Comes in tomorrow so my question is if you download this app and you then get a call to say you have being in contact with someone who has the virus so you self isolate for 14 days which you do,you then go out on day 15 to replenish your supplies and low and behold you then get another call/message to say you need to self isolate again for 14 days as you have been in contact with someone with the virus so where does this end anybody.

Test and Trace! Strange concept don’t you think? It’s all done on a voluntary basis.
Question 1. If you have been in contact are you as a person who has just returned to work/ been allowed to visit your family in a bubble going to inform the authorities after all the emotional trauma you’ve just been through?
Question 2. Who the hell is going to police this?
Question 3. How can they enforce it?