I am struggling to find specific information, but this is our situation:
We applied for a COA at the start of September (1st)
We started planning a ceremony (Just meal and registry signing) for the last week in November, thinking we had plenty of time according to the guidelines on the Home Office website (4-8 weeks)
We still have heard nothing, and now it is too late to arrange a registration, so our plans have basically gone out of the window.
We phoned up, and need to wait 14 weeks before we can get an update. This is not mentioned anywhere on their website and literature, and the COA procedure leads you to believe you will be looking at a maximum of 8 weeks. Thanks ****ing Home Office. You are an absolute disgrace and a shambles. Glad I am seeing value for money from my taxes and not being treated like some criminal or second- class citizen, rather than a higher- rate taxpayer & law abiding citizen

Anyway I digress, the problem we have is that we can not go ahead as planned now, so the question is... If we were to do something in her home country (Namely Brazil)- i.e. a registration, what would we need to do to make the marriage recognised in the UK? In typical Home Office fashion, getting the information I need is like trying to get blood out of a stone.
Is it simpler just to wait for the COA, have her come back on a fiancee visa, and then do it all here?
Also, she is here on a student visa which expires on the 30th November, but her flight to leave the UK is not until the 8th December... Does she have to leave the country and come back as a tourist for that 8 day period?