@umbra21 - Unfortunately that's somewhat of a myth. While that particular building that you're thinking of does have structural beams of oak wood supporting the roof, they were simply cut from an ordinary forest, grown for the purpose of providing wood, but not specifically for that particular hall.
Apparently the best way of growing a forest for wood in England is to have a mixed bag of different trees which come of age at different times, including oaks. While the others might be cut and replaced, the oaks are left until they come of age at about 150 years.
Oxford happened to have such trees around when they needed to replace the ceiling, but they are just there for general purposes, not for that particular roof, unfortunately.
It's still a good example of looking ahead though.