A 65-year-old man presents to his GP with a 3-day history of productive cough, fever and pleuritic chest pain. He is otherwise fit and independent. Temperature is 38.3°C, respiratory rate 22/min, blood pressure 130/76 mmHg, and confusion is absent (CRB65 score 0). His chest examination reveals right basal crackles. What is the most appropriate empirical antibiotic regimen in primary care?