This marks the beginning of a section with just Jack and the Doctor. In my opinion, one of the biggest flaws of the current series (and of some earlier one, Five's Team TARDIS for example) is that there are too many companions and not quite enough plot to hand out. At the moment, Jack is the one with the most plot relevant knowledge, he needs time to naturally be able to impart that. Don't worry, Yaz and Co. will be back.
Summary: The fam and Jack arrive in Cardiff.