No, I don't use 24 hour clock. I don't know anyone who does use 24 hour clock in normal everyday life. You normally only find it used by the military or similar services, or on printed timetables (for example train timetables) to avoid any confusion.
If you do want to use it, then you can't use o'clock with the times. Its always 'h
Normal, every day conversation does NOT use the 24-hour clock. The military does, and says "thirteen hundred" or "thirteen hundred hours," but I have never used it outside of that context.