On the right, you can watch a short video for children that tells the tale of St George in a very simple way. The video has subtitles both at the foot of the cartoon and underneath, in the configuration spur wheel, so it can be understood by B1 students:
It is not easy to find references to Saint George's Day in the British press, but you can try these: an article in the progressive newspaper The Guardian about the historical facts behind the legend of St George, or, on the other side of the British media spectrum, a number of recipes to celebrate St.George's weekend in the conservative tabloid The Sun (both can be recommended to C1 students).
If you want to find children's games and more to celebrate St George's day in confinement, you can visit the webpage of History at Home from English Heritage (C1 level). On the right, you can watch a video of a 2017 edition of St George's Festival at Wrest Park, Bedfordshire, in 2017: