I would hold out no hope considering it’s an EU country. I don’t know if you’ve travelled recently, but between London and Dublin to back home I got pretty much all of my toiletries taken away from me because they didn’t fit into a tiny ziplock bag and that might for some reason cause an explosion in the plane. Not saying American homeland security is any better, but I wouldn’t try to get anything through there. They had a shit fit over my multivitamins and ephedrine.
Even if you can get it in Prague, I would say it’s a mail order deal, bro. Even in China where it’s legal you have to special order it because no one uses it. Thailand and Mexico are pretty much the only places I know of where you can buy stuff over the counter (because they’re both 3rd world countries with a huge market and big profits are made). I would venture to say the chances of being able to find it at the pharmacy (chemist are about slim to none.