Pauline, this may sound idiotic, but cream comes from milk which cows produce. Assuming you have a cow and a supply of milk, I remember when I visited my grandparents, milk was delivered each day and placed in a billy-can. the milk was fresh and did not come in cartons or bottles.

The milk was scalded on the stove (I suppose this is like pasturising) and the cream floated to the top. This was spooned off and left to cool and formed thick cream - not like the stuff available in supermarkets though.

Maybe somebody else has a suggestion for "mock cream" which may be suitable for your pavlova.