Just wanted to echo the sentiment that you should never worry about asking a question here.
And I envy you the variety of cream that you have available -- we have nothing like double cream here, unless we get it from "you" in little bottles at exhorbitant prices.
In general, if you want to add a bit of lemon to cream to sharpen the sauce and cut the richness, you should do it AFTER the cream has been cooked -- either after you boil it down a bit, or after the dish/sauce has been cooked.
You won't poison your family otherwise, just give them something possibly tasty but very, very UGLY!!!