There is no published literature on this particular case of lexical variation.
Although chewing gum is clearly prevalent throughout the whole of the United Kingdom, there are some clear regional patterns that indicate more lexical variation in the North than in the South. 97% of southern speakers use chewing gum, and the other variants are almost totally absent. In the North, however, there are clear clusters of chewy around Merseyside and Middlesbrough, chuddy around Greater Manchester and Leeds, and a suggestion that chud is somewhat more common in Tyneside.
