Buzzjack has the info on biggest girlgroup album debuts!
This is what I have found to be the highest debut sales for an album by a girl group:
191,856 | Spice Girls - Spiceworld (#1, 1997)
155,000 | Spice Girls - Spice (#1, 1996) *
117,967 | Destiny's Child - Survivor (#1, 2001)
85,717 | Girls Aloud - What Will the Neighbours Say? (#6, 2004)
85,670 | Girls Aloud - Out of Control (#1, 2008)
84,354 | Girls Aloud - The Sound of Girls Aloud: The Greatest Hits (#1, 2006)
84,000 | All Saints - Saints & Sinners (#1, 2000)
81,962 | Girls Aloud - Chemistry (#11, 2005)
81,231 | Little Mix - Glory Days (#1, 2016). <<< currently
80,000 | Atomic Kitten - Feels So Good (#1, 2002)
75,787 | Spice Girls - Greatest Hits (#2, 2007)
73,390 | Spice Girls - Forever (#2, 2000)
67,996 | Destiny's Child - Destiny Fulfilled (#5, 2004)
65,781 | Sugababes - Taller in More Ways (#1, 2005)
64,772 | Sugababes - Angels With Dirty Faces (#2, 2002)
63,118 | Sugababes - Three (#3, 2003)
60,053 | Little Mix - Get Weird (#2, 2015)