First, you have a right to be informed by the police officer of the reason for arresting you. If the police officer fails to tell you the reason at the time of the arrest, the arrest is generally unlawful.
Secondly, you have a right to silence. Immediately after the arrest, the police must inform you of your right to remain silent. The police officer will caution you by saying, "You are not obliged to say anything unless you wish to do so but whatever you say will be put into writing and may be given in evidence." You may therefore choose whether or not to answer any questions posed by the police (except that you may need to provide your name and address to the police). Thirdly, every person taken into custody by a police officer must be taken immediately to the nearest police station.
A child or young person should not be arrested or interviewed at school, unless it is essential, which in that case the interview should be conducted in the presence of the head teacher or his nominee.