Hi, passing on concerns will be what the network around you looks like, who you speak to about professional matters. Whistleblowing involves practice in a workplace that gives you cause for concern. ie. where a colleague uses emotional abuse - shouting, demeaning, teasing, taunting, physical abuse, punishment with hitting maybe, neglect ..
Doing it in a way that protects is by speaking to appropriate people who are in a position to manage an allegation following lawful policy and procedure, rather than discussing any concerns openly or freely with others, which may cause victimisation, misinterpretation, deformation of character, spread rumours, harm well-being and damage a relationship that may otherwise resolve problems quickly and positively/amicably. Knowing what it is that gives you cause for concern will help how you're able to protect children and those suspected of poor practice.
This is a good companion read: Protecting children - supporting foster carers
You local fostering service's designated allegations officer who will liase with the LADO
children's services, foster care unit, social services, NSPCC
About making a disclosure in the public interest
whistleblowing on direct.gov.uk
Hope this helps xx