If application is active

Sendkeys is somewhat unreliable at best.  You can use code like this to activate a window before sending keys.  (If the window is already active, no harm is done.)

Dim ProcessID As Integer = Shell("Notepad.exe", AppWinStyle.NormalFocus)
AppActivate(ProcessID)  'Also takes window text, like "Untitled - Notepad"
SendKeys.Send("This is a test")

This is got an in-game thing so send keys is the only way unless you know the API for the game which is unlikley. Is there an if statement that checks to see if it is activated?

Depends.  Could be done with Win32 API depending on how you are tracking the notepad window... How is notepad being run in the first place?  Does it have a window caption we can track?  Could there be more than one notepad window?

And why is AppActivate not appropriate rather than checking to see if the window is active?

Nice.  :)

Thanks mate!