Tourist L changing to a Z visa

I am currently living in China and plan to leave for travel, my L will be cancelled. I will travel south east Asia, then have to come back to work in china for a different company in September, they have advised that I come back on a tourist L and when I'm here we will have a month to change it to a Z, I've heard so many different reports from my Chinese friends that I don't know what to think. With the government always changing the rules everyone seems mixed up? I am English and plan to pic up a tourist L in Hong Kong?