Wouldn't Frederick the Great accede in Britain anyway if George II and descendants were eliminated?
Frederick the Great was born in 1712, during the reign of Anne (reigned 1702-1714). The succession line could be altered if the House of Parliament wished to avoid a crown union. But lets see what the succession line looked like at the time.
1) Sophia of Hanover (1630-1714). Heiress to Anne according to the Act of Settlement 1701. She eventually predeceased Anne by two months.
2) George Louis, Elector of Hanover (1660-1727). Eldest son of Sophia. Eventually succeeded to the British throne as George I.
3) George Augustus, Duke of Cambridge (1683-1760). Eldest son of George Louis, had already received a Peerage title. Eventually succeeded to the British throne as George II.
4) Frederick Louis of Hanover (1707-1751). Eldest son of George Augustus. Eventually became Prince of Wales but predeceased his father.
5) Anne of Hanover (1709-1759). Eldest daughter of George Augustus. Eventually became by marriage Princess of Orange. Later serves as Regent of the Netherlands.
6) Amelia of Hanover (1711-1786). Second daughter of George Augustus. She was a prospective bride for her cousin Frederick the Great. But never actually married, nor had descendants. She spend most of her time "riding and hunting".
7) Sophia Dorothea of Hanover, Crown Princess (consort) in Prussia (1687-1757). Only daughter of George Louis. Mother to Frederick the Great. Became Queen in Prussia when her father-in-law died in 1713.
8) Frederick the Great himself (1712-1786).
He was eighth-in-line for the throne at the time of his birth. He moved steadily down the succession line due to his uncle having further children and descendants. To move closer to the throne, seven people would have to die and the fertile George II would have to end his sexual activities early.