Your most welcome Brimstone. ETO stands for European Theater of Operations. I am including here a couple of links that I think you will find interesting:
The first is a written account of the war time experiences of 309th ECB veteran, Sgt. Alphonse York.
http://www.battleofthebulgememories.be/en/stories/us-army/604-my-experience-in-the-world-war-ii
The second is a video interview of 309th ECB veteran, Corporal John Clarke
http://memory.loc.gov/diglib/vhp/story/loc.natlib.afc2001001.32564/
Both men mention being in England but do not specify exactly where. Even though these links will not answer your question about where he was stationed in England, you might learn some other facts. I know this may not be much help but most all units were embedded in the southern regions of England near ports of embarkation such as South Hampton, Plymouth, Brixham etc. If I ever come across more info about this I will be sure to pass it along.
Have a good one!
Randy