I'll restate this again for those who are slow on the uptake referring to the potential holiday problem in original post.
Although the official line delivered by government and headteachers, both of them flawless in every aspect of their beliefs

, is that taking holidays in school time damages pupils learning. There is not a shred of evidence to support that notion.
The only time a holiday absence makes an impact is if it coincides with an examination.
'Catching up' in any case is catered for by a concept known as a spiral curriculum where topics are taught cyclically and revisited.
New content in a single lesson in an incremental advance and not a huge body of new knowledge.
So, concerned parents having been told that a holiday during school time is inadvisable should enquire when the examination dates are if in the unlikely event that they have not already received an examination timetable and book holidays accordingly. Do it with a clear conscience you are not damaging your child's education.
New knowledge for those who are slow on the uptake - I will not repeat this for those who go on holiday and miss this posting
The main reason why head teachers spin the line about holidays not being wise is that the government has set attendance targets for schools and are used when judging whether a school should be placed in 'special measures'. It does lead to the manipulation of data on absences to raise attendance figures and recent changes to the rule removes holidays from the manipulatable data. I do not want or feel the need to go into this legalised cheating in depth and will leave for those who really want to get to the bottom of the issue to do their own investigations or become a teacher and discover for themselves the chicanery that goes on to 'cook the books'. Government, OFSTED and head teachers do not care about individuals, they are in the business of setting targets and meeting them by fair means or foul, usually foul. The child, the term learner can be used loosely here as a substute, is reduced to the mechanism of delivery of raw data to be fed into the statistics machine.
Those who doubt this should retrain to be a teacher and have their eyes opened to the reality of life in schools in the 21st century. It's very different from the critics own experiences as consumers of education in the dim and distant past when the currency of education was knowledge and understanding.