[I do not own in any way, shape or form, any of the BBC-affiliated television shows mentioned or referenced below.]
Walking away was both harder and easier than Martha had expected [she suspects that the last of the wanderlust that would've tempted her into staying on was burned out right around Japan, but she doesn't want to think about it]. She'd meant every word of it, of getting out, and having people to care for. And so without further ado, she opened the door, entered, and closed it, as if it was just another day. [She ignored how the gate closed with a clang that sounded unnervingly like a Toclofane tearing through a rusted car several dozen yards away.] She smiles at her mother as she walks in, and they all hear the grating noise that the TARDIS makes, as it heads out into the unknown. Martha is acutely aware of what is to follow in his wake, and sure enough, UNIT contacts them about debriefing about the events of the Year. [Everyone involved silently agreed that it merited the capitalization.]
Leo is the one to call them; they'd planned on calling him to break the news to him, but he's very confused and wants to know if his family's okay, because he came back from his walk and heard his entire family was under suspicion and "possibly called in by MI5 on charges of terrorism, what was going on, and were they okay?" Martha's the one who tells him, stony-faced and focused on a very interesting part of the ceiling [the paint's a bit chipped, how did she not notice that?], and answers his questions. She felt guilt over having possibly been the reason [she knew she was the reason] for the Master's interest in her family. [She knows it's not her fault, but. She was so, so sorry, and damn if that didn't make her sound like the Doctor.]
—-
Jack finds her, not long afterwards. It had taken him less than four minutes to find a Martha Jones, living in London, and with an interest in the medical field, when he'd gotten back. He'd also seen the irony of the Doctor taking on a medical student, and couldn't quite smother the [semi-hysterical] laugh that erupted when he'd seen how close she'd been to residency when he'd they'd barreled into her life. He called her up as soon as reasonably possible, and invited her out for drinks if was ever in Cardiff. It soon becomes a habit to call each other, especially after the nightmares. And that's how he finds out.