I'm going through the opposite situation, but hopefully my experience will help. English is my mother tongue, and I immigrated to Israel where the only people who consistently speak English are high-tech workers, cab drivers, and 1 out of every 4 police officers. Of those, only the high-tech workers are in any way fluent. I completed a six-month language program, but I still couldn't speak or even read more than basic signs with any confidence. After 2 years here, I moved from a job for English-speaking immigrants to a job in Hebrew where everyone understood English.

I started working on a few projects with one engineer who reads English but cannot speak it. In a matter of weeks, my Hebrew pronunciation, comprehension, and fluency went through the roof. Since then, I've been started making friends with people at stores near my house, making phone calls to solve things that could be solved with an online form (and Google Translate). I'm still nowhere near fluent, but I gained confidence from being forced to speak and write.

The main thing is, just be prepared to speak, not be understood entirely, and make mistakes. The other day, I accidentally told the clerk at a store near my house that I didn't need a bag because I had large cunts instead of large pockets. We laughed, I survived, and I'll never get those words confused again.