The car has been into the local Vauxhall dealership for an investigation, and the mechanic has stated the car does need the timing chain replacing, but they were unable to tell me which part is causing the rattling as they 'didn't dismantle the engine enough' to find out. When I told Luton about this they stated the mechanic would not have been able to make an accurate diagnosis without dismantling the engine parts to view the chain!? When I picked the car up it did seem to be in the same position on he double yellow lines outside the dealership. I'm wondering if it ever moved.
Luton have stated they will pay for 50% of the £651 bill if I can show them a full Vauxhall service history, which I can't as I didn't get it when I bought the care and the previous owners has moved from the address on the log book.
Fortunately my dad worked at Vauxhalls for 30 years and can get discount on parts so it looks like its going to cost me around £400 to get it fixed.