I've attended several and I'm a .NET developer too. You'll be safe. Yes there's loads of Ruby and Node devs there but in the main people aren't prejudice. My experience is that it's more about ideas and not about language implementations.
I'm not really a .Net (although I've done some C#) guy but I would kill for a bit of type safety in the large python code base I work on! Someone pleeeaaase start a Haskell company in London :-)