Renault Modus engine sounds rough on start up for a few seconds

You can get this " fault" until oil is pumped through engine .Tends to rattle until hydraulic tappets fill with oil to self-adjust the valve clearances .Quite common on that car to have rattle at start up , could also be the camshaft dephaser pulley .If not been done for a while , you could try changing the oil and filter using the correct grade of a good oil and fllter .But may still be there , Also dependant on mileage , could be general engine wear .

Its a Renault its fitted with a dephaser these are known to fail ,on start up the engine makes a rattingnoise that disappears ,as the dephaser gets worse the noise starts to last longer ,and sounds like a tin full nails being shaken up and down ,its an expensive fix requiring a new dephaser appx £120 + new can belt and fit a new water pump while your at it !
Hope it helps !