Basically, I'd be really interested in helping with this mod.
When it comes to scripting/mapping etc., I'm about as much use as a slightly concussed four year-old, but I know a fair bit about Welsh history, so if I could, I'd be more than happy to help with Welsh settlements, historical figures of the period, major historical events and quotes for the loading screens.
I'm also a fluent Welsh speaker, so maybe that could come in handy when it comes to unit names etc.