A 55-year-old woman presents with a 6-week history of symmetrical pain and stiffness in her hands (MCP and PIP joints), wrists, and feet, particularly worse in the mornings and lasting over an hour. On examination, there is swelling and tenderness of the affected joints. Blood tests show a raised CRP and ESR. Rheumatoid factor is positive. What is the most appropriate initial disease-modifying antirheumatic drug (DMARD) therapy according to NICE guidelines?