Nervous didn't even touch the tip of the iceberg for Severus. He was nervous, apprehensive, and skeptical about this request from Lily. It seemed simply too good to be true. It felt like a trap. Perhaps Potter had shown up and Lily was simply drawing him in for a final duel, or perhaps she was being held by Death Eaters who wanted him back. Either way, it was difficult for Severus to resist the urge to show off exactly how much he'd taught himself since Lily had stopped talking to him.
He was still dressed for work in trousers, a long-sleeve dress shirt, and a waistcoat; his hair tied back out of his face. He's been told to either cut it or keep it tied back, and he'd settled for tying it for now. He'd also glamored the Dark Mark so that it would be less visible under the light fabric of his dress shirt. Though no one at work cared if he had a 'tattoo', he was certain it wouldn't go over well with Lily.
He stopped for Chinese and after receiving their order, apparated to just outside of the Welcome Center. He'd passed by the place when he'd first arrived, but it had literally just shown up overnight right before he'd gone and the first person he'd run into had told him that. He hadn't trusted a place like that appearing suddenly and he'd chosen to avoid it until after he'd gotten settled.
He nearly ran into a police box which was placed there and he stared at it for a bit before moving on. It was out of place and odd, and Severus found it curious. But right now, his appointment with Lily was more important. He took the elevator to her floor and found her room rather effortlessly. As he stood staring at the door, he couldn't help but wonder what he was going to come face-to-face with. Maybe she would be younger than he was or perhaps older. Maybe he wouldn't even recognize her. He took a deep breath and knocked on the door as he cradled the Chinese food under his arm.