"What I did was completely wrong."
Simpson was caught about 6.30pm, near the end of his 12-hour-plus shift, and said he had not eaten any food that day.
Asked if he was the worst bus driver in New Zealand, Simpson said: "Believe me, I don't think that's the case."
He had no plans to get back behind the wheel after his disqualification ended.
His biggest regret was upsetting his passengers — a couple of regulars were on the bus when he was arrested, Simpson said.
"I saw on their faces that they were surprised."
He also regretted his actions may have harmed the reputation of Ritchies and his colleagues.
"This isn't a systemic issue. I don't like them being dragged through the mud because of one idiot mistake by one idiot driver."
The drink-driving conviction would be his first and last, he said.
"Learn from what's happened to me. You can lose a hell of a lot."