I agree with mamy 23.23 and I also have sympathy with our Poole headmaster's opinion.
It is a matter of degree, commonsense and knowing your children as mamy has said.
Slight temperature, bit of a cough....dose them up and send them to school as grandparents and parents would have done 50 years ago.
As for the NHS website and the "high ranking GP's" advice....of course, when one throws into the pot...."high temperature, shivering and drowsiness" then that invokes a different "ball game and in these cases one might, need to seek a medical opinion.
Common sense........that's what it is all about.