When trying to open Microtonic in the Free VST Host you suggest I get the error message, Loading Bridge C:\... exe Failed
Please can you help

I think you may be trying to open the 32-bit version of the Microtonic dll in a 64-bit version of VSTHost or the other way around? When you install Microtonic you can choose to install 32-bit, 64-bit or both and you also get to choose in which directories to put them. Please try to locate the correct dll and try again.