They have many job types at Social Services, including Social Workers (SW). There is a lower level job, usually referred to as 'Support Worker', and these people usually spend much of the day to day time with clients, more than the the SW's themselves. Often Support Workers, who show competence, will take on some of the role of the SW's, possibly contributing towards assessments etc.
Quals - Good written language skills and maths, preferably with some GCSE's. A degree for a SW is good, as it proves academic skills. Alof of SW's get paid course fees and time off for training, Masters level degrees etc.
Experience counts for alot. I know an ambulance driver who went on to become a support worker in the mental health section of a Social Services dept, so aptitude / ability, however it can be demonstrated is key.
Getting in is important, as internal moves are easier and you'll see internal job vacancies too. Perhaps your 1st job there won't be the ultimate that you'll aim for.
I'd suggest 'A' levels to start Social Worker training, if you have limited other work experience.
Good luck! Rob