As mentioned above, the tappets on the 1.2 engine are mechanical, and adjusted by inserting shims (thin discs of metal). They will not need any adjustment for 100,000s of miles yet...
But, if the car has sat for four or five days, there will be no oil at the top of the engine - it will all have drained back down to the sump. So, on starting they may rattle as they are not being fully lubricated. Best to let the car idle for a few seconds after starting if it's sat unused a few days, so the oil is pumped back around the works.