I had a difficult wading through the dense universe that is fan fiction. This is what I came up with (source: http://archiveofourown.org/works/285113):
The narrow street on which John lived was dark and silent. John and Sherlock had walked the remaining half a mile to John’s flat together, Sherlock informing John about the science of deduction and how he applied it to the solving of crimes for his work. John had been an attentive and eager listener, only occasionally interjecting with the odd ‘brilliant!’ and ‘but that’s marvellous!’
The two men came to a stop outside a front door that looked as though it could do with a good lick of paint.
‘Chez Watson?’ Sherlock asked, drawing himself up.
‘Ah… yes,’ John said with a nod. ‘I– this has… uh…’ he trailed off and grabbed the back of his neck. ‘Listen, how about that light? And a cup of tea, maybe?’
‘Tea?’ Sherlock said, rocking up onto his tiptoes, his eyebrows lifting. ‘Alright then.’
John grinned and opened the front door. ‘You’ll have to excuse the mess, I’m afraid,’ he said as they both stepped into the dingy hallway. ‘My work doesn’t leave much time for keeping house.’
‘That’s quite alright, John, neither does mine,’ Sherlock said, following John up the wooden stairs. ‘I’m positive I shall feel right at home.’
John laughed quietly as he unlocked the door to his own flat. ‘Um, let me take your coat?’ he said, taking in a surprised breath when he turned to face Sherlock and found him much closer than was usually considered decent.
‘Thank you, John,’ Sherlock said, removing his gloves and scarf, putting them in one of his huge pockets. He maintained his proximity as he took his hat off and handed his heavy coat off to John. Underneath, he wore a sharp three-piece suit with a light tweed pattern in dark grey, a plum-coloured tie fastened around his neck. The top couple of buttons of his shirt were undone, revealing a long white neck that was almost too long. John’s eyes flickered over Sherlock’s skin before he came to himself.
‘Right,’ he muttered, hanging Sherlock’s coat and hat and then his own, taking his suit jacket off so he was just in his practical brown waistcoat and shirt. He unfastened his cuffs and rolled his sleeves up. ‘I’ll go and see to the tea, you…’ he turned around and noticed that Sherlock had disappeared from the tiny hallway and was seated at one end of the lumpy sofa, his legs elegantly crossed, his smirk still in place. ‘…make yourself at home,’ he finished lamely.