I can't see why you'd be having any problems internet related, and you shouldn't have any issues running through VirtuaBox in theory either. (Although the USB support seems to be a bit ropey in my experience).
The firmware is downloaded from a store, there's probably no reason why I shouldn't at some point download it all and package it with the tools. But this way has mostly worked!
There are a bunch of Log files that get generated by the tools: Documents\PhatHack Media Manager\Logs
You can take a look in these and see if there's anything shouting about whether or not the process is truly working.
Where abouts in the UK are you?