car not over heating just a little oil in water.drives like a dream

It would cost u much less to replace all the water with good coolant.then see if the ''oil'' problem returns.

The head gasket itself is cheap.20 to 30 quid? l only know euros. But the labour can be 4 hours.
The mechanic must remove all the little things in his way to remove the ''head'' of ur engine. Six or seven obstructing things.
He must not disturb the timing belt upper pulley.
He must gently scrape all the old gasket pieces from the head & the motor block, without scratching the soft aluminium.
Then reinstall the gasket, maybe he will want to replace all ur head bolts (ten of them) and.
Adjust the valve clearances??? maybe?
Finally replace all ur coolant & oil.

l am guessing 250 pounds in all? guessing. l live in Belgium & do all my own work. Have done the head gasket job about 5 times on 5 Peugeots..
An independant garage will cost less than the Peugeot dealership!