Where can you speak Latin?
If you happen to be learning a modern language such as French, you can - if you have the requisite time and funds - travel to a country or city where it is spoken by residents. The same is not exactly true of Latin. There is no France- or even Quebec-equivalent - where everyone speaks Latin all day, every day and schoolchildren can visit. Believe me, if such a town existed, I’d live there and be the local librarian.
Latin is a language learned primarily with the goal of reading literature, whether ancient, medieval, or early modern (or, if you’re a fan of Giovanni Pascoli, who wrote in delightful Latin as well as his native Italian as recent as the dawn of the previous century, modern in the most colloquial sense!). It is quite necessary for not only classicists, but also anyone interested in Roman history or archaeology, the church fathers, history of Europe and surrounding regions, philosophy, Christian theology, art history, medicine, law, history of science, history of mathematics, and so on. No matter what your interests are, someone, somewhere has more likely than not written about them in Latin.
However, some people learn to speak as well as read because traits required for speaking - specifically, the listening comprehension required to understand spoken language and ability to form sentences - also helps with reading comprehension. If one doesn’t know much grammar, obviously one cannot communicate one’s thoughts in a manner that makes sense to the listener. In my experience, people who speak Latin well read with much greater fluency, allowing them understand and, equally importantly, enjoy the texts they are reading. The point of speaking Latin is to read better, not to speak Latin, as odd as this may sound. See this awesome blog post by Roberto Carfagni for a more eloquent, detailed explanation.
Of course, if there are no Latin-speaking regions, where can one learn to speak Latin? Anywhere, thanks to the internet. Organizations like Schola Latinaoffer online courses for beginners and advanced students. You can also find private tutors, for example on iTalki. I myself tutor using Familia Romana. If you already have some passive knowledge of Latin, you could also join a circulus Latinus, whether in person, like the Ambulationes Romanaein Rome, or online, like CLIO.
I would not suggest trying to learn Latin from the beginning at a summer school or conventicula. As far as I know none exist that are suitably long - you would need to spend a month or two in such a setting, and there isn’t enough demand for such a program to exist anymore. Also, it would be quite expensive to run. However, for students at the intermediate or advanced level, I would certainly suggest seeking out conventicula or summer schools. They tend to be wonderful fun! Plus you can find new friends with whom you can form reading groups online after the course ends. I particularly suggest Schola Latina because their summer schools are the longest currently in existence (a little under a month) and the rustic setting is delightful.
I also made a long list of all the Latin summer schools and conventicula that I am aware of, if you are perhaps curious to read more.