She returned to the ITV show alongside Phillip Schofield, 56, for today’s episode and the pair discussed her upcoming gig.
“When you told me, I just couldn’t believe my ears,” said Phil.
“It’s exciting,” replied Holly.
But the blonde siren then revealed how it’s suddenly dawned on her that she’ll be confronted by “spiders and stuff.”
She confessed: “There are three things I’m not looking forward to.
“One is the eating challenge. Even if you were eating chocolate and you opened your mouth to show me what was in there, I wouldn’t like that.
“The fact you’ve eaten some body part that’s not meant for eating… it’s going to be horrible.”
“What have I done?”
Holly continued: “The smells, I’m not brilliant with smells. And when they come out and they’ve still got stuff on them.
“What have I done?” she asked.
It was announced last week that Holly would be filling in for Ant McPartlin, 42, on this year’s I’m A Celeb.
At the time, Holly said: “I couldn’t be more excited to have been asked to stand alongside Dec for the next jungle adventure.
“I love Ant and want to send him my best wishes and support for a continued recovery.
“When is it a good time to tell Dec I’m scared of everything that moves?”
I’m A Celeb is set to return later this year.