Hello Alec,
There are other ways you can enter notes via a MIDI keyboard than by performing the music at full speed. For example, you can use the Step-Time entry method where you point the mouse where you want to add the note, and then play the note or chord on your MIDI keyboard.
You can purchase MidiNotate with GBP (£) using secure online ordering at
www.notation.com/purchase.htm
Cheers
-- Mark