Thanks for the help. Yep I had to install vs2017.
So I got it working. But when I came to integrating my existing code base I came across a major problem. The Bridge C# library uses its own version of mscorlib.dll I believe and as such it creates circular references with my existing code (which uses the standard libs such as system.dll, system.web.dll, entity framework, mvc etc. I could not for the life of me get them to work together due to conflicting references. The guys over at the Bridge C# project suggested I need to create a Bridge project and add all my code to that. Tried it, still couldn't sort the problems. So... is there anyway you MonoGame guys will use another library or are you stead fast on Bridge? I'm having to look elsewhere for a C# to WebGL solution - probably Unity (which is sickenly complicated for what I want to achieve).