Does the Church of England generally consider the Genesis creation account (first couple of chapters) more metaphor than literal history?
The Church of England has not taken a stand on the simplified 'creation versus evolution' debate. Many people investigating this have reported being unable to find a clear positional statement from the CofE, and there are quotes from church leaders stating that they believe there is no official position. This is an example. The church has made pronouncements stating that a belief in evolution is compatible with Christian faith, but that does not mean that those who believe in a literal creation are excluded from the church.
From personal experience, members of the CofE, both laity and clergy, take a wide variety of positions on the matter. The recent Archbishop of Canterbury has stated his personal acceptance of evolution, but does not see the Genesis creation stories in opposition to that.
So to answer the direct question, the Church of England makes no definitive pronouncement on how much of Genesis is 'metaphorical', but the general position of most of its leaders is that at least the timeline of the first three chapters should not be taken as literal history.
A good friend of mine who belongs to the Church of England (as a minister) explained it to me in the following way:
The Genesis narrative is considered for the most part literal, but the representation of days is metaphorical. This comes from both a Judaic teaching that these days represented ages as well as 2 Peter 3:8:
But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day.
Also Psalm 90:4:
For a thousand years in thy sight are but as yesterday when it is past, and as a watch in the night.
This teaching is also used to reconcile evolution on a biblical basis. Since with all the ages occurring within an undisclosed amount of time, the evolution of various life forms without instant creation is plausible.
This is also referred to as Day-age creationism.
The days as WE know them are literal, as Moses would have written in a way easy for his people to understand. Using metaphors would not do this, especially when we are given regular days throughout the rest of Moses' books. However, as Psalm 90 and 2 Peter show, God is not bound by our idea of time - so a a thousand or million years work to be done in one day by God is completely logial from a biblical perspective.