The barriers to 'breaking the ice' in a situation like this are just as much Lesson plan: download Worksheets: Socialising 1- Breaking the ice worksheets.
For this kind of ice breaker, you can have activities where students mingle and walk about, which can be great for getting up energy and breaking the awkward.
Additionally, the first lesson is also a prime opportunity to build a rapport with the of the students, and this can be done through a number of activities that are fun , All adult students would have an expectation of an English class, and when.
Depending on how your school organizes its classes, you may use these types of activities primarily at the beginning of the school year. You can also adapt.
Adult ice breaker and team building games for the classroom, conference, meeting, 10 Super-Fun Activities for Your First Day of School.