many people use fontina but it does have a milder taste
Lancashire Cheese
No. Plain yogurt is a good substitute for sour cream. A substitute for ricotta cheese is cottage cheese that has been drained of excess water (use cheese cloth or seive).
A good substitute is Caerphilly Cheese from Wales which is a pale crumbly cheese made from cow's milk. It has a similar texture and taste to Lancashire Cheese.
Jarlsberg cheese, Leerdammer, and Maasdam cheese are all good substitutes for Emmenthaler.
Sour cream
I have personally found that Colby works well as a substitute.
You can substitute ricotta cheese for cottage cheese. I don't think it would work with cream cheese.
asiago or parmesan
Lemon juice
I would think not because whip cream is sweet. Sour cream has a more tangy bitter taste to it.
Sure.
goat cheeze or a mild bree` would be good.