There are plenty of them, and most of the mods, depending of course the type of mod it is, are usually just straight up source code themselves. For instance, some are written in python, some in unbound or unbound2, some of the less code intensive mods, like texture mods, are simply xml files pointing to the file to use instead of another file.
There are a bunch of tutorials here.
That's the NA (edit: somehow the .eu didn't clue me in to the fact that it's the EU forum...) EU WoWS forum, and it's in the "Modding Tutorials, Guides, and Tools" section. There is a lot of tutorials, documentation, and guides that you could look at. Personally, just due to you being used to functional programming languages rather than Object Oriented Programming, I'd recommend the free, but outdated, Code Academy course on Python2. Python2 is dead (long overdue too), but the basics that that course, which is interactive, in browser, for free, are all basically the same in Python 3. The differences are subtle, but enough to not be straight backwards compatible. If you don't mind paying, the Python 3 course, as well as the additional "Pro" content, will get you a lot deeper into it, but, for free, go with the Python 2 course. Here's a link to the Python 2 CodeAcademy course. I'm not sponsored by them, nor do I have any financial relationship with them, I've never used pro, I just learned Python2 (coming from Java in high school at the time) almost half a dozen years ago on that, and it's only improved since.
A few tutorials I'd recommend as far as modding WoWS:
ModsApi (Python and/or Flash)
Skin Mod Tutorial
Texture Mod
Unbound How-To as well as the Documentation for Unbound and Unbound 2 and how to integrate Unbound and ModsAPI
ModsApi and ModsApi2 Documentation
Basically, you definitely need Python, and possibly some Flash programming skills, depending on the mod you want to make.