The TARDIS's pool room had significantly changed from how his predecessor used to have it look. It was still enormous, and the open sky still remained, but instead of the columns around the pool, the area was more organically shaped, and the decor had a distinctly tropical theme, with sandy beaches and lots of foliage, and crystal blue water. There was a generously stocked tiki bar in one of the many huts around the "jungle".
When the Doctor heard Missy's voice, he emerged from a grass thatched pavilion over looking the pool.
"Here I am!" The Doctor waved his arm to she could see him; he'd shed his rock star clothes and changed into a bathing suit. "Come on over!" he shouted. "I have drinks!"
Yes, he really didn't want to talk about what Missy wanted to know, and so he'd create a number of distractions that he hoped would delay the inevitable.