Remember, technical skills can always be learned. As a modder of various teams myself, I appreciate it far more when I have team mates who are enthusiastic and committed to see the mod through to completion and who have the time to develop than have technically adept members who never actually produce anything.

Aside from the real hardcode areas of modelling and animations, most RTW modding areas you can progress from being a complete beginner to being an expert in just a month or so.

To do campaign maps all you need is an image programme that can handle .tga files. Myrddraal has an excellent guide to modding the map in the Campaigns & Maps subforum of the Scriptorium.

To become a scripter, the only programme you need is Notepad. Check out the beginner and intermediate guides on the Scriptorium.