I haven’t read the full thread. Is the school trip happening in term time?
The rules for Residential Visits are
Schools can charge for board and lodging but the charge must not exceed the actual cost.
Schools cannot charge for:
education on any visit during school hours;
education outside school hours that is part of the national curriculum or for a public exam;
the cost of supply teachers who cover for those teachers who are on the residential visit.
Schools must make it clear that parents who are in receipt of certain state benefits will be exempt from the cost of board and lodging. The ‘eligibility criteria’ is aligned to that of free school meals.
Education partly during school hours
A school can only charge for activities outside school hours. However, no charge can be made for activities outside school hours if they are part of the national curriculum, a syllabus for a prescribed public examination or religious education.
If 50% or more of the activity time is during school hours, it is deemed to take place during school hours and no charge can be made. Travel time counts in this activity but school hours do not include lunch time.
If less than 50% of the time on the activity is during school hours, the whole trip is deemed to take place outside school hours and the school can charge – for example, an evening trip that leaves school an hour before school ends.
For residential visits, if the number of school sessions taken up by the visit is 50% or more of the ‘half days’ spent on the visit, it is deemed to take place during school hours (even if some activities take place late in the evening). The school day is required to be split into 2 sessions regardless of start or finish times. A ‘ half day’ means any period of 12 hours ending with noon or midnight on any day.
Example: A trip from Wednesday 12 noon to Sunday 9pm will count as 9 half days with 5 school sessions and so will be deemed to take place during school hours. Whereas a trip from Thursday 12 noon until Sunday 9pm will count as 7 half days with 3 school sessions and will be treated as taking place outside school hours.
childlawadvice.org.uk/information-pages/charging-for-school-activities/