At the time of the decision to invade, the decision was between fighting and continuing the sanctions, inspections.
I haven't found a single quote by a world leader, other than Saddam Hussein, uttered before the invasion, stating that his government was confident that SH did not have WMD's. I have spent quite a bit of time googling.
1441 passed unanimously, and implict in that acceptance by the UNSC was that the members were concerned about SH WMD capability.
The conventional wisdom at the time was that we were going to get gassed during the fight.