Maddie:

I assume 'screen wash' was is windshield wiper fluid (Wiki says yea) That would explain things, as it used ethylene glycol for the antifreeze form, and simple methanol alcohol (or ethanol for the eco-brands) Rubbing alcohol from the chemist (pharmacy over this side of the pond) is about the same, but you need the high-concentration stuff (90% +)

Read the label ingredients, it'll tel you what the chemical components are. If it has 'ammonia' too its probably the UK equivalent of Windex. If so you can use it for cleaning your household glass/windows, and even some metalwork.

Thing with the automotive stuff (and more likely in the UK) is it has a lot of water in it. You should use the stuff with less water.

As for practicing, you can buy the dollar store 'latex' kids paint, thinn and strain it for consistancy, and practice on cardboard or whatever. It allows you to practice with ~cheap~ paint, without wasting the good stuff, and without needing to un-do a botched job on your model. Another option is the botched batches from the paint stores - they often sell it off when they bollix'd the shade.

I suggested a better airbrush as the different nozzles & tips allow you to do anythnig from coarse patterns to fine lines. In a pinch, patterns cut in paper or 'foto-frisket' (adhesive sheeting for DIY patterns) can be used.

When in doubt, experiment with cheaper paints and 'target' items. It'll pay off in the end, trust me. But definately look into a powered compressor of some sore, it'll ssave you a lot in the long run. Some of the light automotive ones even come these days with an adapter to attach an airbrush hose. Not to mention airbrushes (when turned up high) are great for cleaning your models too! It won't break off delicate pieces like a brush will.

WhiteWolf