Thanks for the comments. I should really have been able to straighten it out in my head, but sleep deprivation seems to be taking it's toll! The plan is then:
- Leave non-visible faces unplaned (those directly touching the exterior walls).
- House all joints to the ideal timber.
- Plane all surfaces to be planed in one go shortly before raising.
Now to start cutting! I can't express how exciting this is. :-)