It wasn't complicated, but direct and good. She was going to find Ben (who was cute and kind and brave and listened), and she was going to tell him about the Bad Thing. Warn him, which was what the shivers in her belly wanted her to do and what was the logical thing to do because Ben was the kind of guy who would tackle a dragon to save a hedgehog.
(Jubilee said so once, when she was talking about Ben. She'd been smiling while she said it but there had been a funny, narrow look on her face. It was the sort of look that meant she was being more adult than Jubilee.)
She was going to tell Ben about the dreams, the nightmares, and explain how they felt like cold, black pudding dripping out of your skull down your spine. About how all the clocks were making her nervous, and how there was a number stuck somewhere in her throat. Cherry had been living with the awfulness for over a week. She tried avoiding sleep but the house elves put something in her tea. They were always doing stuff like that at the main house, making decisions for you and tattling to Grandfather if you poured the tea out a window.
She would've told Jubilee all of it, but Jubilee had interviews and meetings--and then she had more of the same in America until Cherry had to sneak Napoleon through the fireplace. The elves had ratted her out about that, too. They tried to give her more suspicious tea again but Cherry had kicked the dinner tray down the stairs and locked herself in the Peacock Room instead.
Yes, Cherry had a plan but she was also sleep deprived, hungry, scared, little and alone. So when she finally found Ben, she did the best she could at the moment.