Voice Text doesnt work on the Hero unfortunately. HTC did not include the android.speech package in the Android firmware. Because Voice Text relies on the Google Voice Recognition service, it wont work on the Hero (you'll get an error stating there is no Recognizer present).
The UK thing isn't an issue with the app itself, but with the Google Voice Recognition service. I'm not sure if it's available for the UK yet. I dont know about the UK, but here in the US, when you buy an App, you have 24 hours to uninstall it for a refund.
