hi! there's room for more here on England specifically, but you can get started on these posts
Who named the lion "King of the Jungle"?
How come the lion has become a symbol for so many european countries/dynasties, even though there are no lions in Europe? - also links to the FAQ
Why is a lion so commonly depicted in many European medieval crests instead of an animal indigenous to that area? How many Europeans had actually ever seen a lion when they began being depicted in crests, seals, flags, and shields?