The 25-year-old, who has been tipped to win the reality show by fellow contestant Amy Lame, claimed that she made several mistakes when working in the Monarch Airlines cabin crew for the ITV2 show.
"All the food and drinks were supposed to be complimentary and I put them through the computer as being cash, which was quite a large mistake to make!" she said. "When I did the manual demonstration my hands were shaking, I was shaking so much. But I'm glad I did it."
Glamour model Marsh added that she would consider taking on an airline job full-time: "I don't want to keep whacking them out for a living, I've got a baby girl now, I want to be a good mum and don't want to keep doing that for a living. It's my kind of job. I need to be out and about and doing something different [every day]."
CelebAir, which follows eleven celebrities as they become airline employees, begins September 2 at 9pm on ITV2.