Cheers @deadsparrow!
Here's the good news. Keep practising with charcoal. Drawing is the foundation of painting. Drawing if done right, will teach you to see and understand values which are the key to the illusion of realism.
Further good news. To paint like the Old Masters you only need a few colours. In fact the fewer the better. If you want to go to the extreme, there's the Zorn palette, which only uses four!
So you can certainly set yourself up with the materials you need to paint in oils. You don't need to purchase everything at once. When I began, I only had a few things and over the years have progressively added to it.
If you're interested in creating in a manner like I do, I offer online tuition.