"I would be very careful with drinking and driving as alcohol breath tests are quite common throughout the country (limit is 0.5 grams of alcohol per litre of blood). "
I think you're missing a 0 .... at 0.5 you wouldn't be driving, you may well be dead.
Assume you meant 0.05. As long as you don't drink more than 1 standard drink (small glass of wine), and don't drink on an empty stomach, you will stay under that limit.