Need help with flooring options

Hi there, I'm a conplete newbie to this, but I'm looking to put a floor down in my 6x9m shed. It's currently sitting on a 100mm thick concrete perimeter (dirt floor inside), and I'm not able to get the concrete truck out as the driveway is too hairy. I'd say mixing it by hand isn't an option as I've never done it before.

I've considered yellow tongue particle board on top of plastic pallets leveled and packed in with gravel. I've also considered joists, but don't know how that would work the 100mm depth I have to work with, and the fact that termites are a real threat out here. Does anybody have any suggestions for flooring that would work? Will be living in it for a few years so will only have a few people on it, and no cars. Any guidance would be greatly appreciated.

Thanks I'm advance!