Or... if you record a macro in which you create a new document based on that
template, you can then put that macro onto the QAT so that clicking the tool
would create a new document based on the template, saving you the steps.
Depending on the name/location of the template, the resulting macro might
look something like this :
Sub NewLetter()
'
' NewLetter Macro
'
'
Documents.Add Template:= _
"C:\Users\Herb\AppData\Roaming\Microsoft\Templates\HerbLetter.dotx"
_
, NewTemplate:=False, DocumentType:=0
End Sub
Note: I did not need to modify the recorded macro for it to work perfectly.
You should expect similar ease.
Then use Customize QAT - Macros, etc. to put the macro onto the QAT.