MAITLAND: Doctor, is there no way you can get into your ship?
DOCTOR: No, not unless they return what they stole from my ship.
RICHMOND: But will they’ll never give it back to you!
DOCTOR: Oh my dear, they’re not invincible, no-no-no. Did any of you notice the peculiarity in their eyes?
MAITLAND: No I can’t say I did.
DOCTOR: It’s a fallacy of course that cats can see in the dark, they can’t; but they can see better than we humans because the iris of their eyes dilates at night. Yes…huh! Haha!
Rule #1: The Doctor Lies.
But that business with the Doctor being half human needs a bit more explanation than what you have: there are several instances of Paul McGann’s Doctor using the fact that he’s half human as a plot device. You’ll need to make your peace with that in a more creative way.