I sympathise with you, MissAdventure, for having had to agonise over this issue. It must be very worrying for somebody conscientious.
I gather from oblique references earlier in the exchange that you have experienced family tragedy, with which I also sympathise, of which some Gransnetters seem to be aware. However, some of us who have recently joined will not be aware of your personal circumstances, and it is not helpful for commenters who are aware to beat others over the head for their lack of this knowledge.
For what it’s worth, I agree that missing 3 days before half-term is unlikely to cause serious damage to the boy’s education. I am sure we all have memories of sports days, nature walks and “silent reading” while Miss caught up with her reports in the wind-down to holidays.
The ban on holidays in term time was a huge problem for those of us in the NHS when I was working. Rosters meant only a limited number of people could have time off in school hols, which meant some with children (let alone grandchildren) couldn’t have holiday time with them at all for some of the holidays. And those without school age children (like me for the last 15 years) just never got away in the school holidays. And the contrast between the cost of holidays during the school holidays, and the weeks before and after, meant that lower paid parents could afford to go away in term time, but not outside. One nurse manager thought she would “solve” it by saying that nobody was allowed to book more than 1 week’s holiday at a time!