Welcome
Until you have become familiar with the machines, their use, and measuring, I would suggest making small accessories and tools, rather than diving straight into models.
Making an error on a piece of mild steel will be cheaper and less daunting than an expensive casting!
And, as you learn you can be making tools and accessories that will be useful in the future.
A Centre Height Gauge, a Mandrel Handle, Saddle Stop, or Tap Wrenches will always be useful for any project, and give you experience and confidence..
If you can find a Model Engineering Club within a reasonable distance, joi it. You can get advice face to face, and sometimes members will demonstrate techniques.
Howard