Thanks everyone for your suggestions. In the end I went with HP5+ because it really was the only 400 speed film I could get my hands on (and of course, I'm very familiar with it). Unfortunately the toddler was uncooperative throughout the shoot, so it ended up being primarily the mother. We had nice light in the afternoon and I hope the photos turn out (I'll develop them this week). Unfortunately I don't have a darkroom, or access to one, so I won't be able to print them for a while.

The thing I found most interesting was how much direction my friends needed (the husband was involved briefly until he had to take care of the kid). Even though they wanted pictures, they really had no ideas of what they really wanted in terms of poses. Just another skill I'll need to work on if I decide to keep on with portraits...