I think Gregory's answer is the best option: forget about the which/that dilemma and just add "...in London." Maybe we can use a clearer version to show the difference: "I got it at a vintage store which specializes in 80s fashion." "I got it at a vintage store that specializes in 80s fashion." These are both correct and natural, and mean exactly the same thing. As other commenters have correctly noted, "that" as part of a relative clause cannot follow a comma. "I got it at the store's Charing Cross branch, which specialises in 80s fashion." Only this is correct. Notice that we can remove the whole relative clause, and we still know exactly which shop you mean.

Both are correct, but "which" requires a preceding comma: "store, which is in London." In this way, the relative pronoun "which" refers to what comes before the comma. "That" does not require a comma before it, and is less formal.

In American English, you can omit it altogether. "I got it at a vintage store in London."

This is a difficult one, Which many native speakers get wrong. Native speakers presume they are interchangeable and will often use either when speaking....myself including - but they aren't interchangeable. We use WHICH when we are using a clause that is connected to the sentence e.g. I love the pizza, which I got from a local restaurant. - This is a non-restrictive clause or I love the pizza that I got from a local restaurant - restrictive clause. I believe the American and UK rules are slightly different, but I don't know how Hope this helps Jane :)

the first was is right "wihch"