This study is of twin purpose. First, it tries to investigate the linguistic difficulties encountered by international students studying in the UK in the use of Informal English and its effect on their daily life communication with native speakers. The second, it aims at finding out whether some other extra linguistic factors are responsible for this struggle of using or understanding the Informal English used by native speakers. In order to achieve the major objectives of the study fully, a survey has been designed to explore the main source and reasons behind these difficulties. Fifty, male and female, students studying in the UK, of various specializations, have been chosen carefully to participate in this survey. Accordingly, a statistical method/technique has been conducted to analyse, examine and describe the respondents’ answers. A frequency count as well as a frequency rate is practised to assess the major source responsible for hindering these students to interact and communicate properly with native speakers whether in class environment or outdoor. Furthermore, the study has provided a brief account of how English being global along with some perspectives of Formal and Informal English as well as the differences between the two.