Once becoming King will Prince Charles' wife Camilla become Queen?

(Original Answer)

Technically, yes. Camilla will then be a Queen consort. That means she is married to a reigning King, but has no official powers of her own. However, she very likely may choose to use a lesser title rather than the title of Queen.

By contrast, Queen Elizabeth is a Queen regnant, which means she is a monarch and reigns in her own right.

(Improved answer)

No, because they are technically NOT married to one another. Charles and Camilla were married in a register office at the Windsor Guildhall on April 9, 2005, but it's far from clear that that marriage was lawful. Civil marriages were introduced in England by the Marriage Act of 1836 but in section 45 it says that the Act "shall not extend to the marriage of any of the Royal Family".