Right, before you do the concrete floor, I'd still suggest you think twice. Yes it won't rot, but it's more expensive to do, and it'll be colder to walk on. If you can get someone in to do the work, then I think it'll still work out cheaper. If you concrete it, what will you put on top of it. If you decide on laminate, then you'll need a good quality underlay under it, but if you've got wood, then you can use a cheap one. By the time you've got a concrete floor to a good level, I suspect you'll have doubled the wood floor price, and taken just as long.
You'll only need to inject a DPC id there's rising damp, so is there any evidence of that. How old is the house, and is there air bricks, and a dpc above them.