well, I can positively say that ALL Fiat cars are NOT shite. Golfs etc will cost you a fortune in insurance as we have already discussed in depth. Fiat have specialised in making good small cars for years. The Cinq is by no means fantastic, but for what it is-a VERY small basic run about, it will do you just fine. In an ideal world yes, you'd be buying a Polo or whatever, but your resources are limited because of the insurance. I wouldnt turn down looking at any Fiat to be honest, because I have so far found MY Fiat, to be f*cking brilliant, and probably the best used buy I have ever done and I have had a lot of cars. If you like the Cinq, look at some, and look good. As already said, tiny cars, thin metal, rust problems. Also consider the Panda, which is actually a model UP from the Cinq.
As mentioned earlier, I would still give consideration to a little classic if you can get hold of one. You simply WONT be getting a Fiat 500 classic for that money, but you might find a little 126 BIS..maybe...
as for answering you question, I have driven a Cinq yes, around town they are fine but scary on the motorway because they are so small and light. they are noisy because they dont have much inside to dampen the noise, but other than that they are a decent design for the size, proven engine, just dont expect anything more than a very basic and simple car.
as for parts, they are very cheap in fact, I have found most Fiat parts to be reaonsably priced. Things like radiators, are £30 ish, exhaust, £30 ish, fornt wings £25, brakes/pads £30 ish etc etc you get the jist...