For the Environment modelling, enough drawing skill to make a basic map and asset list (combined with the ability to look up good references of objects) should be enough.
Afterall, you don't need an orthographic reference for every damn rock and cup in the scene.
If you're making a building with pretty basic Architecture, they're pretty straight forward, too. On important, landmark structures, or alien structures you might need a good illustration to work off, but other times you should be able to get everything right with a crude doodle of the building with a stick-figure for size and proportion comparison.
But otherwise, as said above, you'll need to work on very base level proportions (eg, tips of fingers generally come to about midthigh, elbow is at the bottom of the ribcage... that kind of stuff) and anatomy on paper, and maybe do some anatomy sculpts once you get those down. Drawing ability isn't necessary, but it sure helps. You should keep up the drawing stuff, as it's a useful skill to have, but don't get distracted by things like "style" and stuff right now. Just basics.
And to get into the industry, you have to show skill. Be proficient at what you do, and love doing it. Don't worry about if you're ticking all the boxes right now, just learn to do what you want.