Hi Lee
The Zylene is really for thinning or getting the stuff off your hands. It doesn't need thinned for how you're using it, so if you wear a pair of disposable gloves that problem's solved.
You can get it from a professional painter and decorator supplies company if you're desperate, but they normally sell it in 5 litre tins - way more than you'll ever need. I'd send you my 4.95 litres left-overs but the post office get a bit shirty on inflamable liquids. If you're ever in Edinburgh though, just pop in!
Give the floor and about 3-4 inches up on the walls a good scrub with an abrasive cloth or even emery paper to key the surface and make sure you dry it off before applying. I was advised to use an abrasive cream cleaner like Jif but it's a bit messy. Don't just do the floor, coat the first few inches up the way too, and take off any door trims, etc and put them back later. Pour some onto the floor and then use the roller to spread it around - using that wee roller tray's a waste of time.
Check the weather forecast for a dry day, because you'll need to keep all the doors open for as long as you can - the
neighbours were complaining when I did mine! Make sure you apply the second coat before the first one starts to set or you'll have to key the surface again. If there's any left after that, use up the rest on the bits where you think you'll get the most wear.
I bought my latest van from a landscaper who was trading up to a bigger one. I was just getting used to the smell of manure stuck in the rear vent when I did the Protectakote - I'm not sure which one's worst!
Have fun