As far as I know there is no precedent for the wife of the king of the UK not being given the style and title of Queen.
It has caused problems every time a princess became queen to know what title her husband should be given, as the rule is that women take their husband's rank and style. This cannot apply to a queen who reigns in her own right.
Mary Tudor's husband Phillip, was known as King Phillip He was king of Spain. Mary Steward (Mary queen of Scots) was prepared to confer the title of King on her first husband, the Dauphin of France, but the Scottish nobles who attended the wedding conveniently forgot to bring the crown matrimonial with them to Paris. By the time that scatter-brained young woman married Lord Darnley, she had realised that Scotland wasn't keen on the queen's husband being styled king.
If Camilla is still a practising Catholic, it was said that that was the reason Charles could not marry her instead of Diana, then there is a constitutional impediment to her being styled Queen - which disappears if she is formally recognised as a member of the Church of England, and she might even get away with proclaiming herself a member of the Church of Scotland. Princess Anne, doubtless remembering the Princess Margaret could not marry the man she wanted because he was divorced, married for the second time in the Kirk (in or near Balmoral) if I remember rightly. The Presbyterian church of Scotland being less rigid about second marriages than the old fashioned amongst the clergy of the C of E.
We'll have to wait and see, won't we, if the present queen is as long-lived as her mother, Charles may well die before his mother, as women do tend to live longer than men, although Prince Phillip is still in the land of the living, so Charles is probably genetically programmed to live to a ripe old age.