Ok, I solved it! The grommet didn't work for me as it was very tight but thanks for the tip.
I have been hunting this little rattle/creak for 4 months now. It ended up being the A Pillar cover. When your looking at the A Pillar go down to the bottom right of it. Mine was just touching the windscreen so as it was going over bumps it would touch a tad more and make a sound. I first stuffed some tissue between it to see if it stops, and it did! So I ended up taken the cover off and applying some felt on the edge where it touches the windscreen. No more sound!!
I hope this is the same on your car and you get rid of the annoying sound. Best of luck.