to work in social service and to be a social worker is very
different.
Don't think you can be a social worker without experience/necessary
certification.
However, a lot of volunteer welfare organisation provide a variety
of jobs, ranging from marketing and public relations to those that
allow you to work on the ground.
You can also perhaps identify a specific group you would like to
work with
the general community? Assisting the poorer community or
unemployed?
Elderly?
Children?
Terminally ill?
Special needs?
Through this, you can also go to the website of the organisations
offering services to the specific target group, and look at their
job opportunities OR give a cold call.