Seems I am unable to access the DLC. I'm assuming this is because I'm on patch 1.2 but does anyone know if this is the cause? If so, just reinstall the game for 1.5 to redownload?

If you are on Patch 1.2 you cannot run the DLC. All you need to do is verify your game cache and it will replace the 1.2 files and replace them with current patch files. FrankerZ

Tried verifying, saddly that didn't do the trick before posting. Would be a lot faster than re downloading on my 1/2 mb download speed if it worked though. Thanks for the info.