If your goal is 'inexpensive' and you'll only be plinking...skip the free float altogether. It's doubtful you would be able to detect any relevant difference in accuracy during casual use. Same for all other add-ons like aftermarket charging handles and upgraded BCGs.
Save your money for ammo and have fun shooting.
This.
If you want optics on the cheap, I'd get either a Primary Arms M3 or their micro.
If you want a quad-rail to mount stuff on, think about what you want to mount to it - if its just a VFG/light (and this is a rifle just for plinking - 100yds or less), then get a non-free-floating rail (its way cheaper). If you're going to put a bipod on it and you want to do some reaching out to longer distances, you might consider a free-floating rail.
Whether you go floating or non, I'd avoid UTG/NcStar/Leapers/etc and stick with Yankee Hill or Midwest Industries at a minimum (Troy is better, but a little more).
I have no idea what the BCG looks like on JSE's surplus rifles, but you might find out if the barrel-extension/upper is cut for M4 feedramps - that's a nice upgrade. As to the bolt, it can make a difference - things like gas-rings, improper extractor/spring/rubber-donut - can cause malfunctions, but again - I don't know anything at all about JSE's surplus rifles. If the Gas-key isn't staked properly, you can get that done somewhere for almost nothing.
If you want to upgrade the latch - figure it out later and just go with the one it comes with for now (you can add that later if you just really hate the stock M4 charging handle).