The internal divisions and high taxes are likely to dominate the Tory party conference, being held in Manchester from Sunday with the flagship leader's address by Sunak on its concluding day on Wednesday.
As the one-year anniversary of her passing approaches this month, the Cabinet Office unveiled plans for a "fitting tribute" to be finalised by a new Queen Elizabeth Memorial Committee to be chaired by Lord Robin Janvrin.
The Coronation of His Majesty the King and Her Majesty the Queen Consort will be held at Westminster Abbey, followed by a celebratory concert on May 7 at Windsor Castle.
After waiting 74 years to become king, Charles has used his first six months on the throne to meet faith leaders across the country, reshuffle royal residences.