Ever since human beings began to leave their caves with a view to setting up more permanent structures in the mesolithic age they have had to rely on wood. At one point Britain was covered in trees and forests were thick and virtually impenetrable. However, our Mesolitic ancestors soon saw to that with flint axes and rudimentary tools. They felled more trees than we could ever wish to. The argument being that they did not really have a choice. Wood as a building material was born and we can see many examples of post holes at archeological sites that have allowed us to construct replicas.
One of the principal trees used would have been beech and willow. Oak, being so thick and dense, was a material that our ancestors would have loved to have used but the cutting down of such a tree was beyond their flints and it isn’t until the Bronze and Iron age that we start to see the Oak being used more and more.
It is in the early middle ages that the Oak tree starts to dominate the medieval construction landscape. It was the wood of choice for all buildings, or certainly for those that could afford it. It is most likely that you will see the main building or meeting hall of a town or village constructed from Oak. Stone was used exclusively for Churches but in the trusses in the roof and it’s rafters there would be oak protecting the parishioners. It is still effective today as the Oak Beams in this link show.