When you say it has "packed up", what exactly do you mean? Does the compressor kick in when you push the AC button (you should notice the revs change when it does)? The reason I ask is, the AC relay in mine was knackered when I got the car, so the compressor would only work intermittently. I think a replacement part was about £20 from Tegiwa and solved the problem for me. When I took the old relay out,I noticed it would rattle if I shook it, so that might be worth checking. If that's all ok, then a re-gas is worth doing like Hazz said. If nothing else, it'll show you if there are any leaks in the system - I think the condenser/radiator is prone to stone damage.....