The cheap "copy" airbrushes aren't all that good and will annoy you while you're trying to learn. The Iwata Revolution is great, I've had one for a while now but have used Iwata for almost 3 decades and I can't fault their airbrushes. Have used a few others a long the way but the Iwata's are reliable and hard wearing.
Iwata Revolution -
http://www.graphicair.co.uk/products...-Airbrush.html Cheaper than anywhere else.
Compressors not so cheap though.
This will get you going but I'd get the next model up which is the 196 and has 2 motors so will keep up with you better while you're airbrushing.
However if you can stretch to a Bambi compressor from the same place as the airbrush I'd highly recommend them. Silent like a fridge and as reliable as my Iwata airbrush !