The UK has a voluntary merger notification policy - Most other...

The UK has a voluntary merger notification policy - Most other countries have mandatory ones - hence why you have to get approval in places like Australia first (and probably, US, Canada, Japan, etc).   We don't 'need' CMA approval to go ahead.  

CMA will check to make sure the merger does not substantially lessen competition - I'm pretty CMA are just looking out to make sure consumers don't get screwed.  And if they think so, they will issue IGAS with some corrective items, or something like that.  Also remember CMA is UK - so should be completely independent of the QLD courts, they waive the condition so hopefully that court item can be resolved and we are not left in limbo for yet another month.

Looks like there is some onus on IGAS to keep the two companies 'separate' until approval is given/not given, they can still trade as one company, but keep the books and people apart.

From UK GOV:
If your merger is completed without the CMA’s approval, the CMA can investigate your merger after it has happened and it has a number of powers which it can use to:

• prevent the merged businesses from taking actions if it thinks that they might pre-empt its eventual decision
• order that pre-emptive action that has already taken place is reversed
• appoint a trustee at the businesses’ expense to ensure that pre-emptive actions aren’t taken or their effects are mitigated
• force the disposal of a business if the merger is prohibited