The daughter of two writers, Charlotte and Richard Hough, she was one of four daughters — and has two adult children herself: Tom, a teacher, and Lottie, a journalist. Moggach was brought up in Hertfordshire and London, and was educated at Queen's College, London. She has lived in Pakistan and the United States. She graduated from the University of Bristol in 1971 with a degree in English and trained as a teacher before going to work at Oxford University Press, where she met her husband Tony, from whom she is now divorced.

For ten years, her partner was the cartoonist Mel Calman.[2] After his death in 1994, she lived for seven years with a Hungarian painter, Csaba Pasztor. She currently lives in a house overlooking Hampstead Heath in North London.

Novels

• You Must Be Sisters (1978)
• Close to Home (1979)
• A Quiet Drink (1980)
• Hot Water Man (1982)
• Porky (1983)
• To Have and to Hold (1986)
• Driving in the Dark (1988)
• Stolen (1990)
• The Stand-In (1991)
• The Ex-Wives (1993)
• Seesaw (1996)
• Close Relations (1997)
• Tulip Fever (1999)
• Final Demand (2001)
• These Foolish Things (2004)
• In the Dark (2007)

Short story collections

• Smile and Other Stories (1987)
• Changing Babies and Other Stories (1995)
• Ta for the memories (1994)

Short stories

• "Sunday in the Park with Henry" (2008, The Sunday Times Nov 23rd online text)

Screenplays

• Pride & Prejudice (2005)

Teleplays

• To Have and to Hold (mini-series) (1986)
• Goggle Eyes (children's series) (adaptation of an Anne Fine novel) (1993) (Won a Writers Guild Award for Best Adapted TV Serial)
• Seesaw (adaptation of her own novel) (1998)
• Close Relations (adaptation of her own novel) (1999)
• Love in a Cold Climate (adaptation of a Nancy Mitford novel) (2001)
• Final Demand (adaptation of her own novel) (2003)
• The Diary of Anne Frank (2008)

Stage Play

• Double-Take