Hi Gareth,
Thanks for the reply.
I'm very pleased to say I finally resolved the rattle. I managed to recreate the sound while the car was stationary and after much trial and error I realised that pressing down hard on the dash near the A pillar and windscreen totally resolved the issue. I have a temporary fix in place (pic below) but will take it in to Audi for a proper fix.
All the best,
Omar