This whole school intrusion thing is bizarre and overstepping what is reasonable.
I'm a parent, lovingly raising my happy cheerful dc, and if I say he is ill or that I am taking him skiing for four days, as the parent, as far as I am concerned, that is enough. Of the 7 primary years, he had100% attendance in four of them.
My ds' only term-time holiday absence was when he was 4 and therefore not legally required to be there, and I informed the school of the trip beforehand. He was back in class when I said he would be.
He only had two illnesses while at primary school, but one was for two weeks, a bad tummy bug or gastric flu and wasn't fit for school. As his mum, I decide when he can go back, which I did. I also called the school office every morning to inform them of his progress.
But I would simply have ignored the school demanding travel details or doctor's notes. Absolutely none of their business unless they believe there is a serious safeguarding risk, which there obviously was not with my child.
They have no legal right to that information and it is nothing more than small-minded bullying.
Having said that, ds' school were never foolish enough to ask.