Blended cottage cheese will work...as will cream cheese blended with heavy cream...or perhaps with some of the "sooured cream" you can get.
But waaaay back in the dark ages when sour cream was an oddity and considered not mainstream, we used to make dips out of thinned cream cheese. It works.
Linda c

Several possibilities.

Tofu can substitute. Get the soft stuff and whip it through a blender. If necessary, add a little cream to thin it down.

Try draining the yoghurt. Line a collander with cheesecloth and pour the yoghurt into it. Let it drain until the thickness you like. Do not let it go overnight, or you'll have yoghurt cheese, and you'll have to thin it down again.

Cream cheese thnnied with wither cream or the soured cream you have available. Let the cream cheese come to room temperature before whipping it with the cream.

You can also thin the cream cheese with mayo if you like that sort of thing.

BTW, don't they still sell clotted cream in Jolly Olde? Check that out as a possible substitute.

I think Creme Fraiche would be a perfect substitute. I use it in stroganoff instead of sour cream. Also use it as a fruit dip. It's thick and a bit tart, we love it.

2 cups heavy whipping cream
2 tspoons buttermilk

Pour the cream and buttermilk into a large jar. Cover and shake vigourously for about a minute. Let stand in a warm place until thickened, about 12 hours. Stir well and refrigerate for 24 hours. Will keep 7 to 10 days.

Note: If you can get buttermilk just add 1 TBSP vinegar to 1 cup regular milk

I second the use of creme fraiche, or quark...

I have seen American style sour cream here....I think it comes from Ireland, otherwise the creme fraiche we buy is from France. (Won't use the French accents on the words as they sometimes don't work here.) Cornish or Devonshire clotted cream may work if you can sour it a little. It's lovely stuff but maybe missing the tang you need for a dip.

SharonCb

Have you tried some better type salad dressings....blue cheese, ranch flavors, etc (often found in the refrigerated section here)? Some of the better ones here are quite thick, but if too thin, you could mix in some cream cheese.

I guess though, it really depends on the specifc dip(s) you are trying to create. I would think you may want a different substitution based on the specific dip. Are you after an onion, spinach, ranch, artichoke or something else, and what is the recipe you'd like to duplicate?

thanks for all the ideas. I wondered about creme fraiche, or clotted cream but didn't think I'd get the taste of sour cream (never thought to combine the two)

I brought back some dry ranch dressing pkgs from "home" this summer so I want to make that and my step daughters like the layered nacho dip. Thanks for the tips everyone.

Diane

You can make your own sour cream pretty easily.

Here is a link that might be useful: How to make your own sour cream