Giedroyc initially feared author David Nicholls disliked her performance during rehearsals, but he was actually moved to tears by the show.
The musical, based on Nicholls' bestselling novel and the 2006 film, is a coming-of-age story with an Eighties-inspired score that took 12 years to develop.
Starter for Ten premiered at the Bristol Old Vic in February 2024 and was nominated for Best Musical Production at the UK Theatre Awards.
The production is set to return to the Bristol Old Vic in September for a month-long run before moving to The Rep theatre in Birmingham.