War planning commenced in mid-to-late 2002 in advance of any UN resolutions or Parliamentary votes. The war was a fait accompli. Bush and Blair wanted a resolution explicitly authorising military action due to Saddam's non-compliance, didn't get one, cobbled together a case for war based on existing resolutions and a threadbare WMD threat, and went for it anyway. The only thing about war planning is that it can be argued it is contingency planning as they may look similar, but it will take disclosures from some very senior people (as for Gen Dannatt) to get to the truth.
I remember perusing the dodgy dossiers on the internet and laughing about the lame WMD claims with colleagues in the crewroom....
WMD threat from modified SCUD missiles....it is very difficult to weaponise a chemical or biological agent for effective delivery. Take anthrax for example. Very nasty but deliverable in spore form which is incredibly difficult to ingest. Also, none of this is much use unless delivered with clear strategic or tactical effect in mind - degrade enemy performance due to wearing IPE, use blood agent to degrade canisters, then nerve agent - and central to this is the ability to deliver the agent effectively with some degree of accuracy and precision in significant quantities.
A missile could hit Cyprus....yeah, if the wind was behind it and they got really lucky! See point above.
Some WMDs could be used in 45mins....rubbish. Saddam killed a good number of his own troops in botched chemical attacks. Out of date Soviet/Warsaw Pact doctrine/C2 procedures regurgitated by a single source, as we all know thanks to the Hutton inquiry and others (even if they didn't join the dots).
Credible WMD threat....why then, did I speak to colleagues in more than one theatre (within supposed range) whose units were either stripped of IPE or collective protection equipment for delivery up-threat or who did not possess enough IPE etc, in particular NBC suits which require periodic change? This touches on wider issues of ill-preparedness: troops without body armour, troops crossing the line without anything near their ammunition issue, SP artillery without desert filters. I was involved in a UOR which wasn't signed off until the war had started (attempt to keep things under wraps to placate Labour MPs).
I respect the arguments of those who support regime change, but that was not the basis for the war. This country was taken to war on a false premise, using intelligence manipulated and disseminated as propaganda. As time passes and some of those involved start to speak out (like Gen Dannatt) it may become uncomfortable for certain individuals. We're due a decision on the release of the pre-war Cabinet minutes...should be interesting reading (I reckon they'll be leaked if not released, as for the Attorney-General's initial advice).
As an aside, I was working closely with US colleagues during the period, and their opinion was that "it was about oil".