This happened to my dd - someone in her nursery bubble tested positive.
We got a letter from DOH / PHE stating that she should self isolate, but the rest of us could carry on with our usual activities - older dd still went to school. DH and I both took a couple of days off work as one of us needed to be with dd.
Thing was, it took nearly a week for the test result to come back and nursery to be notified, so in the end, the rest of the bubble only needed to isolate for 7 days at it had been 7 days since the child had been at nursery (I think they were erring on the side of caution as he wasn't symptomatic at nursery, just a couple of days later).
It's the same at school - one sibling could be isolating if their class bubble bursts, while the other in another class is still expected at school.
To be fair, we are quite stringent anyway, so we didn't have any concerns about her isolating, just meant we couldn't have anyone in the house other than the family.
If dd had developed symptoms at any point, we would have all strictly isolated, but the guidance was clear that only she needed to isolate unless she developed symptoms, and the rest of us were expected to carry on as normal.
OP - I would have thought your employer would have guidance, but if PHE said it was fine for you to go to work, I'd expect you'd need to have unpaid leave to cover if you are unable to work from home.