The Whizz80 computer software library is rather bare at the moment due to the system simply not existing as of yet.
While you could develop on a virtual machine or a simulator, I have not found one as of yet that is suitable for a custom hardware platform such as the Whizz80. Once the hardware is at a level where simple programs can run on it software should then become available to run on it.
So in the meantime I can outline some goals