This explains where you can download a copy of QGIS with NIWA's under-development plugins included (and why you might need to).
As some plugins require modifications to core QGIS to work (eg: some C code for performance reasons) even if some of the tool is still implemented as a Python plugin, until the tools reach a production stage they will not work with the various stable releases of core QGIS. To try these plugins, you need to download the NIWA development version of QGIS with the extra code & plugins built in. Our developer, Sourcepole AG., in Switzerland, has a copy of an installer you can download and run to run NIWA's development version.
It is available here.
Just download the binary installer (exe file) and run it to install and test/use it.
If you have any questions or feedback, please email: Brent.Wood@niwa.co.nz