The question that has to be answered is the scale of the threat that Iraq presents to the UK and the West. Threats consist of capabilities and intentions. There is past evidence of Saddam's will to use WMD. Is he able to develop a capabilty that might seriously threaten our way of life in the UK (chemical & biological weapons being the most likely threats).
The answers to these questions lie exclusively with the intelligence services. To answer them publicly would destroy the sources. Therefore we HAVE to trust our political masters, who were democratically elected as our representatives. Tough, but there it is!