You should be fine to drink at 6 months post-op, I have had wine and vodka without a problem. Be careful of fizzy & sugary mixers as everyone else has said.
Disclaimer - I do feel compelled to say the following as you mentioned that you will be drinking and then driving. If you have not had a drink in 6 months, you do not know how *you* specifically react to alcohol. I personally get very drunk very fast but then *feel* sober pretty quick once I stop drinking. I say *feel* because scientific research has proven that bypassed patients retain a higher level of intoxication for a longer period then a normal person so you could have one drink feel completely sober, drive, get stopped and be done for drink-driving due to your blood levels. It is a risky thing to do when you do not know how you will react. Just thought I would warn you to be safe and think it through. As always, use your best judgement and make the choice you feel comfortable with as you are a grown person, please don't feel I am having a go because I'm not, promise, just trying to be helpful!
Nic