Welcome - I see you're a guitar player. There's a few around here and I'm a bass player.

Fashion and nature work on a pro level uses very different equipment, but you can learn alot from a manual 35mm SLR camera. Something like a Pentax K1000 or a Nikon FM (or many others including Canon and Olympus) and a few lenses like a 24mm wide angle (for scenic outdoor) a 50mm "normal" lens and a telephoto somewhere between 85-135mm (for nature but also good for portraits). You wouldn't even need a flash right away while you learn about working with natural light.

The good thing about buying an older manual camera like this is that the camera and compatible lenses will be very inexpensive compared to current autofocus systems. The bad thing is that you'll have to replace it all if you go with an autofocus and/or digital system someday - but you can probably sell what you have for close to what you paid for it so I wouldn't worry too much.

Check the Studio Lighting forum for ideas on lighting and how to get nice results without spending a lot of money.