A 45-year-old previously well woman presents with fever, productive cough and pleuritic chest pain. Her temperature is 38.4°C, respiratory rate 22 breaths/min, blood pressure 120/70 mmHg, oxygen saturation 95% on room air. Auscultation reveals right lower zone crackles, and chest X-ray confirms a right lower lobe consolidation. She has no significant comorbidities and can be managed in the community. According to Australian antibiotic guidelines, what is the most appropriate first-line oral antibiotic regimen?