If we take Alison Tyler as the mother of Rose, her son could be Mickey Smith (Rose's ex-boyfriend) or Rose's son. If the son needs a top, maybe in a storyline where Rose's son (from the Doctor) needs a top. But the Doctor has a child, the Master (Doctor 6), but that's a different story.
The "needs a top" part is a bit confusing. A "top" could mean a clothing item or an energy top-up, like the TARDIS's top? But likely, the user is referring to clothing. So, perhaps a story or adventure where a character's child needs a top. Considering possible crossovers or fan fiction scenarios.
I should respond by clarifying the possible confusion in names and then offer information on the relevant characters. If the user meant Rose's son, I can discuss that. If it's Luke Smith, I can talk about his adventures. Also, if "top" is a typo for "top-up" in terms of the TARDIS's energy, but that's a stretch. Alternatively, "top" as in a cap, like in a game of Top Trumps, but that's also a stretch.