Mrs Clark, who is in her 50s, finishes at the school this week, after just over six years, to head to Abu Dhabi in the United Arab Emirates.
She was looking forward to the trip, which would involve working with other teachers to help improve their skills.
She had always wanted to work overseas but the timing had never been right, until now.
It was a little scary but also exciting, she said.
Mrs Clark, who came to Ardgowan from Taieri Beach in 2001, said she would miss the pupils and staff at the school.
She believed the school, on the outskirts of Oamaru, was one of the best resourced in the area.
The buildings were superb, along with the IT equipment, and the physical environment was also great, she said.
The best part of the school was the staff, who were "excellent", and she was trying not to think about the last day of term on Friday because she knew it was going to be a sad day.
The school year in Abu Dhabi starts in September and Mrs Clark, along with a contingent of New Zealand teachers, will fly over next month.
She was unsure of her plans once her contract, which was for either one or two years, finished.
Senior teacher Julie French will be acting principal at Ardgowan until a new head is appointed.
