To start, I would not go to the dealers Col! you are talking big money just to look, call at your local family run garage & ask them to check for you. Has the car been running bad? put some REDX Injector cleaner in your tank & give the car a good blast if you have a motorway or duel carriageway nearby.
On 1.5DCIs EGR valve should open to allow carbon dioxide, which acts as a cooling gas) into the combustion chambers when the engine is under load (>30% boost). This allows the combustion chamber temperature to drop and thus the temperature of the exhaust gases. If it sticks in the closed position the exhaust gas temperature will rise causing a) the turbo bearings to fail and b) engine oil into the induction system. This can cause the engine to run on its crankcase oil until it is either stalled or goes bang. Problems with EGR valves in Renault dCi engines are often the cause of rough running when the valve is stuck in the open position as well. In several cases turbos have blown but the EGR valve has not been replaced. Inevitably the new turbo unit will not last long.