FACT: Any amount of alcohol you drink will affect your ability to drive.
By how much can depend on a number of different factors, which include the type of alcoholic drink you’ve been drinking, your weight, sex, age, how much you’ve had to eat and so on. That’s why the only safe option is not to drink ANY alcohol if you’re planning on driving and never offer an alcoholic drink to anyone else who is driving.
It's much safer not to drink at all than to try to calculate the number of units you’re drinking before you take to the road. You could easily find that you're actually over the limit without meaning to be.
If you risk having a drink and then get behind that wheel, you could pay for it for the rest of your life...
If you’re convicted of drink driving here’s what you could stand to lose:
Even worse than the above, you could kill or injure someone. If you do, you're looking at anything up to 14 years in prison. And you'd have it on your conscience for the rest of your life. Could you live with that?
It's not just as a driver that you take a risk. If you get into a car as a passenger when the driver's been drinking, you're risking your life. If in doubt, don't get in and find a safer way to get home.
Legally, the alcohol limit for drinking and driving is 80mg/100 millilitres of blood. In other words, two pints of normal strength beer or ONE large glass of wine could put you over the limit. (Source: UK Department for Transport Road Safety Think!)
If you've had a heavy night drinking, you may still be over the limit the next morning. If you drive you could be prosecuted, so don't risk it. Remember it takes your liver an hour to process one unit of alcohol (e.g. half a pint of beer or half a glass of wine) and flush it out of your system.
It's a common myth that coffee sobers you up. This isn't true. Caffeine in coffee and fizzy drinks is a stimulant, so it might make you more alert, but it won't make you sober.
For your body to fully recover from the effects of a heavy night of drinking, you should avoid alcohol for a full 48 hours.
Source: http://www.knowyourlimits.org/