“During filming, production visited Herne Bay to film various scenes on the pier, beach, and town centre,” a Kent Film Office spokesman told National World. Whether it be a Queen tribute band or the Beer on the Pier bar — which sells craft beer “beside the seaside” — the Herne Bay Pier is known for hosting family fun.
In the series, the protagonists attend the fictional Truham Grammar School, which is actually Herne Bay High School on Bullockstone Road.
Source: https://www.distractify.com/p/netflix-heartstopper-filming-locations