My personal development teacher gave me a very good piece of advice when I was at school:
If you are not fully prepared to face
all of the consequences of having sex, then simply do not do it.
Additionally, what is to stop a man always wearing a condom even if his girlfriend is on the pill?
At the end of the day, pill or no, it is the responsibility of BOTH people to make sure that pregnancy is avoided if it is not wanted. Of course, adults completely abstaining from sex is not a realistic approach, but BOTH parties doing what they can to minimise unwanted pregancy is.
So just wear a condom - it is not perfect, but it got me through many years of sex without a single unwanted pregancy
I feel that a woman being on the pill is not an excuse for the man to not do his part as well.