I understand the grammar, but I freeze when speaking to my Tamil-speaking colleagues

I’m a false beginner—I can read signs and menus, but as soon as someone asks me a question in Tamil, my mind goes blank. I don't want to use apps anymore; I really need to focus on speaking output. Could I use a service like Chickytutor.com to simulate office scenarios and help me build the confidence to stop freezing and start speaking naturally?