Answer
Do not drive if diazepam impairs alertness, coordination or judgement. UK law provides a medical defence in some circumstances when a prescribed medicine is taken correctly, but never permits driving while impaired.
Sources for this answer
- UK GovernmentUK Government · Reputable Web
- Diazepam 5mg Tablets — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.