His son Prince William, Duke of Cambridge who is second in line to the throne.
If Queen Elizabeth dies, then Prince Charles.
If Prince William is alive after the death of his Grandmother Queen Elizabeth II and his Father Prince Charles he will become King.
When the Queen dies, Charles automatically becomes King. However, there are controversies surrounding that there might a generation skip meaning William, 2nd to the throne & Charles' first born, would become King instead of Charles.
If Charles dies before Queen Elizabeth dies, then Prince William will be first in line. If Charles dies while he is king (having succeeded Elizabeth to the throne), then Wlliam becomes king and his eldest son (supposing there is one) will be heir to the throne. If William does not have children, then his younger brother Harry will be first in line.
Prince Charles the Queen's eldest son will suceed to the throne of England etc when the Queen dies.
The heir apparent to the throne of The United Kingdom is Prince Charles.
Prince Charles cannot become King until his mother, Queen Elizabeth, dies. or abdicates the throne
probably when Queen Elizabeth dies it will either be Prince Charles or Prince William on the throne.
When she dies or becomes too ill to carry out the duties of the sole monarch on the throne. I don't think it would be "proper" for her to just retire and do her son the favor of abdicating the throne so he has more time in power. She could to that but it would be scandalous.
That is only if she wants to give the throne to Charles. She could bypass Charles and give it to William instead
When the queen dies or retires princes charles will have the decision to become king or pass it down to william. And if charles becomes king then if he dies or retires william will be king