"helping" is somewhat common here in America. I probably use it once every month or two. By the way, after words like "first", "second", and "third", use singular nouns. Bob just got a third job. Sally asked for a fourth helping of cake.

"Second helping" is used, but not as commonly as "seconds," "thirds," fourths," etc. (meaning to return for more food a second time, a third time, etc.).