King Charles’ team is reportedly planning the cancer-battling monarch’s summer diary. The 75-year-old is currently battling an undisclosed form of the disease, diagnosed after he had an operation for an enlarged prostate in January – and he has been forced to largely step out of the public eye and down from royal duties as he undergoes regular treatments for the illness. But a source has now told People he is “positive” about his cancer treatment, with his staff turning to his summer schedule as there has been “amplified confidence” about his condition in light of the sophisticated treatment h…