EMERGENCY: I can't find double cream ANYWHERE!! Is it the same as "heavy cream?"
If not, do you know any stores that carry double cream?
Yes, Tesco carries double cream. So does Sainsbury's. And Harrod's, of course and most every other store in England, Scotland, Wales, and Ireland that sells groceries. But double cream, with a butterfat content of 48% is not produced in the United States. The best you can do here is heavy cream, which has a fat content of 36% to 40%.
Use heavy cream (perhaps a little more cream than the recipe calls for and cut back proportionally on some other liquid, if that seems practical) and hope for the best.
And calm down a little. At the rate you're going you'll probably curdle any cream you find....