There is an ECU update to raise the tickover a touch. Could be worth asking a local dealer how much they'd charge for an update - Don't let them insist on a diagnosis, as that's just an excuse to charge you more.

But before that, have a look down the left hand side of the engine at the pulleys and belt at tickover, if there's any noticeable 'wobble' then it's the tensionner that's knackered. Change the tensionner, belt and crank pulley. If it is that it's not urgent, as cars can go on for thousands of miles making a racket.