A 32-year-old previously well man presents to his GP with 3 days of fever, productive cough and right-sided pleuritic chest pain. He appears mildly unwell but is haemodynamically stable, saturating 97% on room air. His chest X-ray shows right lower lobe consolidation. He has no significant comorbidities and takes no regular medications. Which oral antibiotic regimen is the most appropriate first-line treatment in this community setting?