Tony.
If the water pump was not replaced at the same time as the belt as it should have been, that could be the source of the noise. As Steve said, get the car to a garage ASAP, because a belt failure is usually sudden and the consequent engine damage can be catastrophic.
Opinions on belt duration, even from Audi, have changed over the years. I would stick with the older 70000 miles recommendation for peace of mind. It's an expensive job at £700 but a lot cheaper than a new engine.