YAY! I got it to work, I was stupid for not realising FindWindow doesn't find child windows.

Working code below.

Code:
#include <windows.h>

main()
{
	HWND Notepad;
	Notepad = FindWindow("Notepad",NULL);
	HWND NotepadChild;
	NotepadChild = FindWindowEx(Notepad, NULL, "Edit", NULL);
	SendMessage(NotepadChild, WM_KEYDOWN, VkKeyScan('c'), 0);
	SendMessage(NotepadChild, WM_CHAR, VkKeyScan('c'), 0);
	SendMessage(NotepadChild, WM_KEYUP, VkKeyScan('c'), 0);

	/* HWND Notepad;
	Notepad = FindWindow("Notepad",NULL);
	SetForegroundWindow(Notepad);
	keybd_event(VkKeyScan('C'), 1, 0, 0);
	keybd_event(VkKeyScan('C'), 1, KEYEVENTF_KEYUP, 0); */
}