I'd volunteer, but I can't make any promises in terms of deadlines since we had a family emergency and it's hard to commit to spending time on "extracurricular" activities in the next week or two. Can you send me a PM with what you have in mind, or send me a link to the fanfic?
Also, I'm not big on Johnlock, especially if it's graphic/explicit content. I might still be able to make you a graphic, as long as it doesn't have to be explicitly slashy.