Spoiler photos and video after the break.
After nearly a week of interiors, filming continued on episode 9 today (the one with the creepy graffiti), with a possible explanation for why we haven't seen much of the Doctor during this story. I guess he can't blame this one on the Logopolitans.
More set pics are available on www.doctorwhotv.co.uk and from colseywolsey1, but it looked like they filmed at least two scenes, one with the Doctor and Clara walking around the half-size TARDIS, and one with Clara alone, talking to someone on her cell phone, with the micro-mini TARDIS.
It wouldn't be too much of a stretch to imagine this story as being a sort of reverse "The Lodger" where the Doctor is trapped inside the shrinking TARDIS, and Clara has to run around on her own trying to save the day.