

I’ve used https://changenow.io/ several times to get XMR from LTC or vice versa. It’s always worked for me, but I’ve heard of people’s transactions being held if they were large amounts, so exercise caution.
This doesn’t solve the problem of buying the initial crypto, which may or may not be difficult, depending on your jurisdiction.
You could get started with Qt, specifically the legacy widgets. There are bindings for Python available (pyside or pyqt) if you don’t want to learn C++ or another language right away. You can also port your GUI definitions to other languages at a later date.