If the intention is to have Camilla named as "Princess Consort" they had better get their skates on and change the law! Changing the Law is serious business and we can expect it to take some time during it's somewhat tortuous passage through both the Commons and Lords. Throw in a couple of Select Commites, submissions, etc. and you've got a country in turmoil. At that point Politicians are wont to look to their own immediate welfare.
The notion of civil unrest can have a galvanising effect on a politicians who can see their immediate future in terms of a snap election. I cannot see any MP pushing it with indecent haste without a clear mandate from his or her own electorate. So, as things stand, should Her Majesty die unexpectedly soon, Charles will be King, Camilla his Queen.
At that stage I can hardly see the Queen lying in state whilst the political machinery tries to make a rapid law change. It would be neither dignified nor respectful to a country in mourning. So, we wait a while until after the funeral and take another shot at change but, what about the King? Is he not to be Crowned until the whole mess is sorted out?
More importantly, what about his Queen, because Queen she will be regardless of whether a "Coronation" service is held. Even more importantly, what about the health of the political party in power? Will they even be re-elected or will it be won by a landslide and at this point neither of the main two parties are sure which is which!
What about the health of the nation, is it internationally perceived to be in crisis? Will the Commonwealth stand stauch or, will it collapse forever?
So the fact remains, as things stand legally, Camilla will be Queen Consort whatever she is called.