The following two activity packs are from Plazoom and are free:
“Each St George’s Day KS1 and KS2 pack includes:
An easy-to use PowerPoint featuring comprehension text and questions, perfect for whole-class teaching
Handy PDF versions of the comprehension text and worksheets for more fluent readers to use independently, or in guided groups
Teaching Ideas has some free banners and resources.
Watch the amazing story of Saint George Today, Saint George according to legend, was a Roman soldier of Greek origin and officer in the Guard of Roman emperor Diocletian, who was sentenced to death for failing to recant his Christian faith. As a Christian martyr, he later became one of the most venerated saints in Christianity, and was especially venerated by the Crusaders. George’s parents were Christians of Greek background. https://www.youtube.com/watch?v=urosZ3PKFJg
For young children, there are resources available from Little Owls.
There is a code-breaking maths activity from Mathsright