You’re running a 3.0TDI V6 up front, so you’re dealing with a heavy engine. It’s not just age, it’s how the car is driven and the reality of British roads. We’re not suggesting to completely refresh the suspension, but unfortunately this is the reality with multi link suspension. If you were renewing lower front arms, do both, front and rear arms. As suggested, these are usually hydrabushes, difficult to tell if they’ve failed unless you see a leak, or get in with a pry bar. I’ve read snake oil remedies about silicone sprays on bushes to remove squeaks. That will be short lived and probably age the bush given it’s petroleum based. The only grease you can use with rubber is red grease. Similar to brake rebuilds. You could try on some of the ARB bushes as it’s a relatively cheap fix, but does mean a little bit of work if your spanner handy.