I've chosen the Starbug from Red Dwarf as my choice for exterior. My reasoning for this is that not only is Red Dwarf a classic British sci-fi series much like Doctor Who, because Starbug’s Series 7 iteration was technically a TARDIS, as it had a working time machine onboard, but as a result of their deaths from their future selves in the Series 6 finale, the Starbug from future merged with the present day one, causing the interior to become much larger than the exterior in order to cope with the paradox.

Some pictures of Starbug for those wondering what it looks like.