Its good that you have highlighted this as many parents do not realise this.
They have to pay for the first year,but after that as long as the children attend school throughout the year,there is no charge.
The school has to give a written statement,which confirms that the child has been in full-time education..........I assume there is a form that the schools have to complete.
I told some friends about this,and they are busily obtaining the needed school documentation and have had it confimed by the powers that be that this is correct information