You might consider sending your razor out for sharpening
Since you already have the razor and don't want to spend much until you know straight razor shaving is something you wish to pursue, you might consider sending your razor to one of the sharpening experts on this list.
Several people here will sharpen a straight razor for a very modest fee; although if your razor is in need of serious rework it might be more expensive. You'd be in a difficult position to sharpen it yourself with the limited tools you have in that instance, anyway.
The experts on the list could make your razor as sharp as possible, thus giving you the easiest and best experience for learning on a straight. I know of my own hard-won knowledge, the learning curve of straight shaving is much more difficult when you're struggling to learn both sharpening and shaving at the same time.
BTW, I'm not representing myself as such a sharpener, I'm still new to straights, too.
KD