I recommend this article by Michael Mansfield QC in the Law section of today's Times.
He sets out our hopes for the outcome:
"This inquiry should have as its core question — how it was that a sophisticated, multifaceted parliamentary democracy failed to detect, let alone prevent, such a misconceived and costly military adventure? On this, there has been a singular lack of scrutiny and accountability. Particular sections of the public, servicemen and women and thousands of dead, injured and displaced Iraqi citizens have a right to know, with a full public explanation and protocols for change."
goes on to detail its many procedural failings, for example:
"What would have led to a better understanding of the whole of this process was an opening statement, in public, by the inquiry about where it was going and what information it already had. This task is normally performed by a team of lawyers who are thereafter enabled to ask focused and pertinent questions."
(No lawyers are on the inquiry panel.)
and ends with the statement:
"The truth is rarely pure and never simple but without it lessons will not be learnt, let alone remembered. This inquiry must ensure with all the means at its disposal that the truth is sought and found."