It would be cool if they found the garage in the episode
Bessie could be parked in there. Don't ask me how.
In the scene where River takes a dive off a building, the Doctor brings her onboard by 'parking' the TARDIS on its side in midair and yelling for Rory and Amy to open all the doors to the swimming pool. River makes a splash as she plunges into the TARDIS.
I have assumed that any room in the TARDIS could be 'rotated' around within the ship's internal arrangement to match up with an external door. I guess the Police Box and the doors would need to get a little "rubbery" to open wide enough for Bessie to enter or leave the garage, though.