The man that does most of the leading edge skins for the Spit is Bob Cunningham. Bob is getting up there in age now and Im pretty sure his wife Simone is now doing the majority of the rolling. Ralph Hull can also do them., but his past is something that should be thought about before approaching him for any work. ( Ask Vintage Wings how their wing build from him went). Supermarine engineering do not do wing builds. Airframe Assemblies I would avoid if you want anything done in a timely fashion.
The go to guy in my opinion for any wing work would be Ian Ward of VMI Engineering
http://www.vmiengineering.com/. He is by far the best spitfire wing builder out there and the also the most professional. I'm pretty sure he uses The Cunninghams for his rolling. He works closely with Vintage Wings on their wing build and if you need any wing symmetry checks, Vintage Wings have an excellent Jig. I think its the only one in North America that is correct. It should be available in a couple months.