Hi, welcome to the site. One agency name could be your Local Safeguarding Children's Board - LSCB or maybe the NSPCC which is a national organisation. You will need to ask your setting how one of these is involved with your setting, you may also find they'll be able to tell you about other agencies they work with xx
For example this is York's LSCB website
http://www.saferchildrenyork.org.uk/
Best wishes