Not sure if this is the correct place to request this, but the BBC weather lookup is not working in the "Weather Report 1.0" widget (bug 430643). Therefore, may I suggest adding the UK Met Office as a data source. They have an API documented at https://www.metoffice.gov.uk/services/data/datapoint/api
Linked bug has been fixed, plus more search improvements with https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/1191. Closing.