A 72-year-old man presents with gradually worsening urinary frequency, urgency, nocturia, and a sensation of incomplete bladder emptying over the past year. Digital rectal examination (DRE) reveals a moderately enlarged, smooth, firm prostate. PSA level is 2.5 ng/mL (age-adjusted range <4.0). What is the most appropriate initial pharmacological management according to NICE CG97?