Written by John Kruse, one of the leading experts on Bailiff Law, this consumer friendly guide is essential reading for anyone who comes into contact with a bailiff.
The book is easy to understand and clearly explains the rights
a bailiff has, and also what they cannot do when collecting debts and repossessing goods etc.
The school can withhold money to cover their costs, however they should also mitigate their losses. If they happen to get another child to go in your child's place and that child pays in full, their losses would be zero and you should get the money back. However if they cannot fill that booking, the school will more than likely have to pay the holiday company reasonable damages, which you will have to cover as it is you that is in breach of contract and not the school.
Please note I'm not insured in this capacity, so if you need to, do get official legal advice.