Why does my Vauxhall Corsa make a loud rattling noise when I start the engine?

I recently purchased a Vauxhall Corsa and I've noticed that when I start the engine, there is a loud rattling noise that lasts for a few seconds. It goes away after a while, but it's concerning. What could be causing this and should I be worried?

The rattling noise could be due to a worn out timing belt or tensioner. It is important to get this checked and replaced if needed, as a broken timing belt can cause serious damage to your engine.

Another possible cause of the rattling noise could be a faulty spark plug. This can affect the performance of your engine and should be replaced as soon as possible.

It is also possible that the rattling noise is coming from loose heat shields. These can be easily fixed by tightening or replacing them.

Based on the information provided, it is difficult to determine the exact cause of the rattling noise without seeing the car in person. It is best to take it to a certified mechanic for a proper diagnosis and repair.