Thanks a lot for those comments DTR, very useful.
Not having been in UK for yonks I didn't know that Humbrol make acrylics too. Their enamels are (were) very good but may not be child proof (the customer for the tractor - which I'll post soon, promise) has just turned 2 so I didn't want to take any chances with someone else's little bloke poisoning himself!
If you do go to a compressor may I suggest you get one of the "silent-er" ones (diaphragm ideally), and also, one with an on/off switch (would you believe on mine you have to pull the plug out of the socket every time! - we don't have switched sockets here).
Also, re an airbrush, the cheapo Humbrol/Airfix air brushes that used to be available in UK are quite good within limits (although they're known as "droplet distributors" by the experts). I have one which, PROVIDED you get the thinning down right - trial and error, are quite good enough for an overall coat of single colour or clear acrylic varnish after colouring. But if you can stretch to it, I'd recommend a single action outside mix brush as an ideal cost/utility compromise between the real top end artists (dual action/internal mix) brushes and the above droplet distributor. I have a Badger 350 which is excellent, but others such as Paasche and DeVilbiss make them too and I believe are equally good. I read somewhere that there's some new Japanese stuff available too.
Not sure about price, but I think my Badger costs about a hundred quid these days. If you use it enough, well worth the investment IMO.
Lastly, make sure the hose from the compressor to the brush is the bigger-bore jobbie, flexible plastic/neoprene inside and cotton braided outside, and with a moisture trap. And ideally but not essential, with a pressure regulator valve on the compressor too. In my experience, unless you're spraying really big toys/models, a reservoir tank is just not necessary.
Googling around some of the specialist model maker Forums and kit suppliers will soon put you right.
Thanks again for your comments and I hope the above is of some help/interest.
Happy New Year
AES