I bought a breathalyser couple of years ago. Any reasonable amount of drinking or late night and you’re not right to be driving at 8 or 9am. A proper session and you’re over til lunchtime.
China, about €10/12. Accurate enough but you need to keep good batteries in it for maximum efficiency.
You of course have the rural option of the concealed emergency supply strapped to your leg for consumption at your leisure in the back of the squad car.
The emergency here would be an officer you weren’t familiar with 30 miles from safety.
Should be ok after 4 or 5 if 7 or 8 hours between last drink and driving. It falls dramatically next morning so if you were bagged any delay at all to a test would help. So if stopped and asked if had anything to eat or drink in last 20 minutes could say yes to get you those few minutes.
A few big deep inhales and exhales before a breath test also helps if it is next morning and you’re borderline.