'You don't have to' was the next thing he was about to say when she stopped him. He was fully aware that he was not particularly tactful when it came to initiating these kinds of things - it was a simple yes/no question for him; a matter of pragmatism with no hidden agenda, but she might not have perceived it that way.
But then she accepted his offer, and he managed a small smile. More relieved than smug or amused, really.
"I will get another key cut." Wasting little time with floundering, he went straight back to practicalities. At minimum, she would need a set of keys, some clothes and perhaps some food now that accessibility to what were once sparse resources was a non-issue. Having access to your own clothes had an understated effect on the mind - Preston had felt homeless in the TARDIS, aimlessly wandering through someone else's wardrobe, taking up residence in someone else's... machine, or whatever the blue box was. Though he would not consider the city 'home', having his own things in his own space brought a type of comfort he could not easily put into words.
"We can spend the day in town finding you some clothes and food." 'If you had no other plans,' he held back this time. He thought he might be making things artificially awkward between them with all these hesitations.