yes, most Local Authorities have different Social Work Teams for different service user group, though how this is organised does vary from area to area.
Generally, the main specialism are Children and Families or Adult Services (Community Care). Within these two main groups there can be other specialist teams for example Youth Offending or Fostering and Adoption within the Children and Families umbrella there can be specialist teams working with mental health problems or the elderly. There are loads of other examples.
Have a think about it, and perhaps use your placements to get general experience which will look good on your CV. Remember when you graduate and apply for jobs you willbe applying for vacant posts so you are best being able to demonstrate transferable skills so its best to try and get placements that give you general experience rather than being in a very narrow field with only limited job opportunities.
Good luck, its a tough but great profession