It’s impossible to post a bottle of vodka (legally) from the UK to the Czech Republic.
Two of the many courier companies I contacted insisted that spirits are illegal in CZ. There’s conflicting information on whether this is true or not. Or, more usually, just won’t ship alcohol as a matter of policy.
In any case, no one at all will ship anything by air which has an alcohol content over 25%, even though this doesn’t seem to be a problem on passenger jets.
Richard WM Jones 
I can assure you that spirits are legal in the Czech Republic 🙂 A year ago, there was a case when three dozen of people got poisoned to death because some illegal alcohol producer spread a spirit which accidentally included methanol. Because more and more people were getting killed and the police didn’t have an idea how spread the spirit was, they temporarily banned all spirits with >20% of alcohol. But the prohibition only lasted for a month until they secured most of the spirit and arrested the illegal producers. Since then, spirits have been legal again. Just rules are a bit stricter. Every bottle sold needs to be documented where it was produced, who bought it, who sold it,… There are no restrictions for a bottle you give someone as a gift though, especially if it’s just one bottle.
The alcohol problem is that passenger jets are under pressure, they are supposed to support human beings. For cargo, you may have aircraft that are not under pressure (normally only the cockpit is). This means if the bottle bursts the alcohol vaporises and may catch fire.
I guess it is possible, but difficult, so the companies stay away from it. Maybe you can find a company which is spezialised in CZ?
I’m highly dubious that freight jets would not be pressurized. Everything would be popping and exploding left and right if this was the case. Don’t know if you believe Yahoo Answers or not, but: http://answers.yahoo.com/question/index?qid=20110610033950AAAIgYI