Do I need qualifications?
Not usually, no.
Some volunteering opportunities require certain skills such as counselling which may require qualifications but organisations often provide training. If particular qualifications are needed in order to take up the volunteering role, the information should be available on the organisations' website.
Often the organisation is looking for personal skills, such as being able to get on with a wide variety of people, being reliable and being enthusiastic about a particular interest or cause - rather than academic qualifications.