You have booked the holiday and are therefore going, with or without the schools permission.
We did something similar when our eldest was in P1. It wasn’t to take advantage of cheap holidays, but we needed to travel a long way to a family wedding in Bristol which was happening just few days before the end of term. Rather than travel back for a couple of days of school we made the most of it and stayed a few extra days. We did howover make a point of doing educational type stuff when away. We went to local museums, historical sites and the brilliant @Bristol. I’m not claiming that we were able to offer the same as school, but it just felt like the right thing to do. Our holidays are always busy and I know the kids get a lot out of them so I didn’t really feel at all bad about her missing school.
To put into context as well, she had never been late or missed any other days, including zero sickness.
My point, if you are going to take your kid out of school, make yourself feel better about it by making the most of the holiday ‘experience’