In the last chapter of I’m the King of the Castle, what were Kingshaw’s emotions before he committed suicide?

Charles Kingshaw's in a terrible emotional state prior to his tragic suicide. Today is the day that he'll be heading off to school with the loathsome Edmund. Edmund has been bullying Charles for virtually the whole duration of the story, and the two boys being sent to school together will provide this truly horrid little boy with even more opportunities to treat Charles like dirt.
Charles feels trapped and doesn't see a way out. To make matters worse, Edmund slips a threatening note under Charles's bedroom door, telling him that "something" will happen to him. It's all rather ominous, to say the least. Little wonder, then, that Charles feels so utterly terrified at the prospect of such a miserable future that he contemplates taking his own life. In a moment of clarity, Charles realizes that there's only one way he'll ever be able to escape Edmund and that's by killing himself.
It's notable that Charles's final act upon this earth takes place in the wood, the only place where he's ever felt safe or secure. As he approaches the wood, Charles becomes strangely excited; this is his place, the place he knows and understands. Here, well away from Warings, where Edmund is the undisputed king of the castle, Charles is in his element. As he ventures deeper and deeper into the wood, a sense of calm descends upon him before, finally, he makes the journey from this world to the next.