Bought the car second hand 6 months ago and the rattle has been there since the start. It seems to be inside the door - if I put some pressure on the door panel it stops. 

Any tips on things I can try to solve it myself without having to take the door panel off? I'm sure I'm not the only one who has had this. 

Daffy question, but I assume that there is nothing in the side door pocket?  The padding they put in at the factory is rubbish.  Best to put in your own additional padding - using something like this stuff:

https://www.amazon.co.uk/Scratch-Motorcycle-Motorbike-Luggage-Passenger/dp/B00DVP0HSG

 

 

Cheers for that! I am 99% sure the pocket is empty, will will have a look to make sure there isn't something small in the rattling around.