Please note I didn't have any pictures to look at at the time I made this, I basically created this from memory, still hope it's accurate. Only thing I didn't add was the glass trap, of course that can be added using redstone.
As exterior, I suggest using the already existing Shed Exterior.
Very nice but a bit small
As I wrote above, I couldn't remember what the TARDIS looked like exactly. I hope if you increase length and width by two blocks you get a bigger interior.