The most useful website, that now has an app as well - National Online Safety and their Wake Up Wednesday campaign:
Lots of information for parents about keeping your children safe, from the experts – CEOP http://www.thinkuknow.co.uk
The think you know website for parents www.thinkuknow.co.uk/parents
Inclusive digital safety for parents and carers of SEND, have experienced being in Care or LBGTQ+: https://www.internetmatters.org/inclusive-digital-safety/
Making a report to CEOP https://www.ceop.police.uk/Ceop-Report/
Reporting a violation to Facebook https://www.facebook.com/help/?page=204546626249212
Making a report to Twitter - https://support.twitter.com/groups/56-policies-violations#topic_236
Lots of information for parents – http://www.parentsonlinesafety.com
Staying safe from Hate: http://educateagainsthate.com
Net Aware - a site where parents review and rate social media apps and sites based on the features and how appropriate it is/isn't.
Digital Safety - a blog post that gives an overview of several dangers on the Internet and how to deal with them, such as child online safety, social media safety, etc.
Online Social Media Tips for Parents: http://www.internetmatters.org/social-media/