ParentinfoThis site from CEOP has articles covering a range of online safety issues. Has guides to setting filters on YouTube and how to set up privacy on different apps.
Parent ZoneHas guides including game ratings, Fortnite and how to restrict viewing on Netfilx / Amazon Prime.
Get Safe OnlineThis site has advice on a large range of topics covering safeguarding children online. Also offers advice about other online issues such as how to protect your computer.