Provided that the chameleon circuit is working correctly (which the one in the Doctor's TARDIS is not), a TARDIS can take an extremely wide variety of disguises. There are, however, some restrictions. The main one (that we've seen) is that the outer shell must be large enough to have a usable doorway.
In "The Time Meddler", the Monk's TARDIS was disguised as an altar & he had to crawl on his hands & knees to get in -- but (until the Doctor sabotaged the thing) he could get in. We've seen the Master's TARDIS & the Rani's TARDIS use fairly small disguises but, again, large enough to allow access.
In "Attack of the Cybermen", the Doctor's TARDIS took some rather strange disguises &, though these were still large enough for a doorway, the Doctor had trouble finding the entrance.