bexx, a good simple one that is also suitable for couples is Mother Massage - Elaine Stillerman. She also has another book that is available for pre-order that I will check out.
Also Carole Osbourne-Sheets - Pre and Perinatal Massage Therapy is OK - but is American and somewhat conservative.
I also highly recommend Shiatsu for Midwives by Suzanne Yates - not specifically a massage book - but very detailed and informative. Suzanne also runs some very good courses - see[link=http://www.wellmother.org]www.wellmother.org[/link]
Hope that helps
InTouch