Introducing her daughters Xanthe and Zena for the first time, the former Countryfile presenter told Hello magazine she had to 'pinch' herself after giving birth.
The star, who already has a three-year-old son Zephyr with partner Gerard Cunningham: "It's my dream come true and I feel incredibly lucky.
"I still pinch myself and think, 'I'm a mother of three.' All the effort, everything we went through as a family, is more than worth it. "I had been very happy throughout the pregnancy but there was always this cautionary shadow on my shoulder that something could go wrong.
She said she is ready to 'step up' to the challenge of having two new babies, adding: "There's the challenge of taking care of them at the same time, the physical demands, but I don't think the concentration required for being a parent to twins is any different.
"I just have to be the best parent I can to all three of them, love them all the same, make sure they all feel that equal amount of attention. You can never imagine being able to love a child more than you do but you do. There's this bottomless pit."
• You can read the full interview in the latest issue of Hello! on sale now.
More on Parentdish: What having twins is really like