A 60-year-old man with type 2 diabetes and hypertension is found to have microalbuminuria (ACR 5 mg/mmol). His blood pressure is 145/90 mmHg despite being on amlodipine 10mg. According to NICE NG138 (Type 2 Diabetes) and NG136 (Hypertension), what is the most appropriate next step in managing his blood pressure and renal protection?