I have just taken my 3 year and 2 month old (yep just out of warranty

) 147 into my local dealer because the air bag warning light was on.
That wasn't too pricey, just a wiring problem but they have also told me that I need new front brake pads, a new handbrake cable and the cam variator replacing.
The pads and handbrake cable is fair enough but I am not sure about the cam variator. As they quoted me £540 I rang a private Alfa specialist garage in Leeds who are going to look at it and if it needs doing will do it for £365 + vat which is a bit better.
Basically before I fork out all this cash is there any way I can tell myself if it actually needs doing. Both garages have mentioned that it is a big job as you have to remove this and that (I'm no car mechanic!) but basically they just said that it is making a noise and that is how they can tell it needs replacing.
Can I check this noise for myself? What am I listening for and when? The 2nd garage said the engine needed to be cold for them to tell how long it makes a noise for.
Also assuming it does need replacing does this price seem fair for the work involved? Is there a cheaper option, bearing in mind I know nothing about engines so would only consider doing it myself if it really is a simple job that I couldn't mess up.
If there is anyone out there who knows about these sort of things I would be very grateful for your help.
Thanks,
Richard