Im pretty new to game engines and i was wondering if I could use python, c and c++ in udk. I've tried getting the answer all over the internet but the answers i do find aren't very clear. So am i able to use the aforementioned languages without the use of plugins or special downloads, and please mention any other languages already built into udk.
For the majority of everything you should be doing in UDK, gameplay wise, you will be coding in UnrealScript. UnrealScript is its own language which resembles Java and C++. You can control the player, the camera, create and modify items, and even extend the editor with custom Kismet actions among other things with UnrealScript. It's really powerful and will likely fit most of your needs. The biggest thing I've seen people be limited on with UnrealScript / out of the box UDK is networking since there is a limit of 64 players per server.
That being said there is a feature called DLL Bind which allows you to call functions from DLLs. This is then implemented by calling the methods from UnrealScript code. This is how you can go beyond the hard limitations of the engine without getting access to the source code, but you'll be starting from scratch and rather limited to how you implement your custom systems because you are bound to calling these methods from UnrealScript as much as possible.
Outside of this, if you actually want to view / write source code for UDK in C/C++ you have to purchase a full Unreal Engine license which is generally way out of anyone's price range with the exception of those with AAA budgets.
So to finally answer your question: you can kind of sort of use other languages (C/C++ being the main ones) but you really should stick to UnrealScript.