Might sound a bit odd but outwith weekends and school holidays there’s a decent chance the kids area at Galleries South will have no children in it. With the door closed the area is fairly sound proof to the outside world. If it’s empty it might be an option although it may not be the comfiest if you’re on a long call perched on a seat designed for a 3 year old.

I’d also agree with CWS. The far corner overlooking south security is usually relatively quiet and with very few other people around and there’s a coffee machine and bar area to hand. It’s my go to area when in Galleries South.