Hi All, so I thought i'd give you an update as you were so kind to reply to me. So, i've had a second opinion. The cam belt has definitely snapped, but it is pure coincidence that it's happened. It looks like whoever fitted it before i bought it a year ago, did a very bad job and it's been rubbing on something, taking chunks out of the belt over time. The car had been running fine for me, so i think it's just finally given up the day that i dropped it off at the garage, when they started it up to take it inside. I have spoken with Alfa Shop Norwich, very helpful people by the way, and they said with the diesels, it might not be as catastrophic as it would be with petrol. So on their advice, I have asked the garage, where the car is at, to strip the engine down a bit to check whether or not the rockers are broken and the valves are bent. If the valves are fine then easily fixable but will still cost roughly £700 ish to do, (better than having to buy a ****ty new car). I will find out on Friday what is happening with it.
Regarding the overheating, once i've found out about the engine, i will ask them to check the water pump as that has possibly seized.
Just a note also to say that any troubles in Norwich, I can highly recommend Smith Brothers Garage on Waterworks Road, Elliott of Car Auto Haus, and The Alfa Shop. Everyone i've spoken to have been super friendly and have gone out of their way to help me!!!