Mackintosh went to Royal Holloway University in Surrey,[1] taking a degree in French and Management, and spent a year in Paris as part of the course, working as a bilingual secretary.

[5] In October 2016, the French translation of I Let You Go (Te Laisser Partir) won "best international novel" at the Cognac Festival Prix du Polar awards.

[citation needed] In March 2024, Mackintosh published a memoir, I Promise it Won't Always Hurt Like This, inspired by her son's death in 2006.

Her son Alex contracted meningitis and suffered significant brain damage, and was allowed to die naturally after spending some time in intensive care.

She is patron of the Silver Star Society, a charity supporting the John Radcliffe Hospital's work with families facing difficult pregnancies.