Surrey, England, specifically. (And if you’re befuddled to discover that Andrew is an Englishman playing the New York native Peter Parker, then boy, do we have some news for you regarding Tom Holland.)
Technically speaking, Andrew does have U.S. citizenship. He was born in Los Angeles to his British mother, Lynn, and American dad, Richard Garfield. However, he moved to Surrey, England when he was 3 years old.
Source: https://www.distractify.com/p/why-does-andrew-garfield-have-a-british-accent