A 52-year-old female presents with a 2-month history of joint pain and stiffness affecting her metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints bilaterally. The stiffness is worse in the morning and lasts for over an hour. Blood tests show a positive rheumatoid factor and anti-CCP antibodies. What is the most appropriate initial disease-modifying antirheumatic drug (DMARD) to offer, according to NICE NG100?