Whatever you do, don't get the floor paint from B&Q, even the stuff they label as trade is rubbish. Mine is peeling up in great patches (I'm going to use my pressure washer to get it all up) and replace with something else.
As has been said, the paint that comes as a 2 part mix is loads better - if you go in the majority of Wickes stores, you'll see some strips across some of the floors between the tills. Some (obviously all the ones that still look good) of those will have been made by me fitting the security tag detection kit about 25 years ago, which has since been replaced again but I went in my local Wickes a good few months ago and the paint was still there.
And as has been said, preparation is the key!