They are still constructing some houses using oak framework over here- saw one going up in the Dordogne. I was told that green oak, whilst easy to work, does shrink a lot and that has to be allowed for. Whether that will be a problem in Wales I don't know, but here the humidity can get very low. The particular chap I was told about put a new upstairs floor in his house and found that the oak beams shrank so much they nearly dropped out of the wall sockets. Something to watch out for perhaps SWB.