Sealant isn't too tricky right enough so if you were worried you could get a penetrating sealer painted/mopped on. HG would do one.
There is a lovely big floor scraper on B&Q that will take someone's head off I can recommend.
Also, have you seen the concrete floor? You may require some sort of levelling screed if it is very uneven (trowel finish if it's the 70's top face) again though not difficult.