Complex sentence: In 1999, Halliwell wrote an autobiography "If Only", in which she described her life as a Spice Girl, this went on to top the best seller lists and sold over a million copies in the UK alone.
Split into simpler sentences: In 1999, Halliwell wrote an autobiography "If Only", in which she described her life as a Spice Girl. The book went on to top the best-seller lists and sold over a million copies in the UK alone.