A few notes from GAF's resident Catholic theologian.
A) This is the bishops of England making a pronouncement. This is not the same as saying "The Catholic Church says". That doesn't mean it's necessarily wrong, mind you, but it doesn't have the weight of the full Church and the Vatican behind it. Local groups of bishops have done various things in the past, including condemning Galileo and approving the Spanish government's executions during the Spanish Inquisition.
B) The pronouncement does not say that the Bible is held to be myth, NOR that any part of the Bible is false. What is does say is that some parts can't be read literally, either because of the style they were written in or because of misconceptions or limitations of men writing them down. In other words, while certain events can be taken allegorically, it doesn't mean that the events are to be assumed to be "made up". Rather, they could the recountings of a man of an ancient event of which little is known... OR, they could be based on understandings of the day.
(Vague example of this sort of thing: assigning names to the first parents [Catholic doctrine still holds that all humanity came from a single set of parents], human understanding of the creation of man [if you believe that God can give man insight into his own origins, some things might have to be explained allegorically and symbolically. I always saw evolution from lower life forms and such as, allegorical, being made from the "dust of the earth". But that's just me], and saying things like "the sun rose in sky" (as we all know that the sun DOESN'T rise, but that's how it appears to humanity. Is it literally true? Nope.)
C) The gist of the pronouncement is that the Bible is written in many different ways, but it is not written like a modern history book. You have to understand the writing styles and the viewpoints of those writing to really understand the text. Revelations was written with heavy allegory, but it isn't false. The oldest parts of the Old Testament were written from a limited human understanding of the realities of creation. The Psalms were written as poetry, and are sometimes exaggerated expressions of love.
None of this is any different than what the Church has taught in the past, really. It IS different from the Protestant understanding that developed during the past several hundred years, and most especially from the fundamentalistic perspective.
(And, in case you missed it, I want to again point out that the point is that you can take EVERYTHING to be literally true... which doesn't mean that anything is false, but that you have to understand what you are reading and what the point is. "The sun rises in the morning" isn't literally true, but someone writing it in a historical book is not being inaccurate in any meaningful way to the reader.)