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.