I've used a bottling bucket as primary before, but that's just because it's a huge bucket and has alot of space in case of excessive krausen.
Personally, I recommend having at least 4 vessels. 2 6.5+gal primaries, 1 or more 5-gallon secondaries, and a bottling bucket.
But if you're cheap:
Typically the lid seals are set up so that you can use it as a fermentation vessel, but you should check to make sure you have a rubber seal. I'm going to assume that your lid has a little hole with a rubber grommet, or at the least, a hole to accept a small bung. Given that assumption, here's a way to find out how good your seal is before you even add beer: snap the lid on tight all the way around. Insert the bung (if needed) & airlock. Make sure the airlock has water in it as is typical. Now, watch the airlock, and push down on the lid. If you get movement/bubbles, then you have a fine seal. If not...get a new primary. And if you don't have a hole in your lid, you can always drill your own. I recommend making it just big enough to accept the smaller (5/8") bungs. Make a practice hole on another piece of scrap plastic first, though.
However, like I said, I recommend getting at least another vessel. You'll want another for secondary conditioning/clarifying. You shouldn't be going from primary to bottling bucket unless it's a hefe.