OK, its finished (for now!).
Hex and .arduboy files can be found here > https://github.com/filmote/Nineteen43/tree/master/distributable
Source code can be found here > https://github.com/filmote/Nineteen43
I had a lot of help along the way from @Pharap He answered many dumb questions - especially with regards to pointers pointing to arrays of images in PROGMEM - and the occasional intelligent ones. Oh right, the intelligent questions were the rhetorical ones he asked himself! Thanks for your help.
Hope you enjoy the game and the music that goes with it.
During play: D-Pad controls the plane, A to shoot and B to roll the plane and avoid enemy bullets.
Introduction: B to toggle sound, Up or Down to change levels, Left or Right to see credits.
Game Over: Up and Down to reset scores.
Level 1 is capped at 30 games.
Level 2 is capped at 60 games.
Level 3 goes forever!
Feedback and suggestions for improvement welcome, complaints less so.