Ok after some digging I got to the bottom of this. It seems that I need to have .Net Core Installed. However when I go to install that I get the same error. The workaround is to run the downloaded .exe from the command line with the added parameter:
DotNetCore.1.0.0-VS2015Tools.Preview2.exe SKIP_VSU_CHECK=1
This will install the latest version of Web Tools as well.