Thanks to the Reddit community and OMG Ubuntu, i was able to circumvent the closed beta access restriction for Steam and i managed to install and run the Steam client. Most of the games in my library were not available as they did not have Ubuntu versions. Of the games that were available only three actually installed correctly; Amnesia, World of Goo and Spaz. I've played Amnesia before on Ubuntu and it was a large download so i didn't test that game. World of Goo worked flawlessly and Spaz ran but had no sound.
The client is still very buggy with plenty of font rendering issues and regular crashes but it's certainly usable. Once all the bugs have been ironed out and all the Source Engine games have been added, Ubuntu will be a very attractive gaming platform. Steam Big Picture appears to be a media centre interface ready for Ubuntu TV or perhaps an in-house developed, Media PC, Linux distribution. At the moment there is no support for videos, music or photos in Steam Big Picture but gaming and surfing the web has been catered for.