In a candid interview, Simon said: "If you'd seen me 18 months ago and said 'Simon, back at home now you've got two dogs and a six-month-old baby', 'I'd go 'Yeah, right!'
"It was never going to happen, but it did. And I'm enjoying my life now."
The dad-of-one, 54, went on to say he is really enjoying spending time with Eric now the little boy can recognise him.
He added: "The first five months were weird. Eric didn't have a clue who I was - I could have been anybody.
"But the last two weeks have been good - he's started to recognise me, and as everybody knows, I demand recognition!
"He's a cutie. I had a really nice day yesterday, working from home, with him and the two dogs in the garden."
You can read the full interview in this week's Radio Times, out now.