Speedster are modeled after the 356A, which didn't have a full filler on the fender/wing. They're all filled through the front trunk ("frunk"). The T6 body was the first to have the fuel filler access through the fender, but that came out in '63, I believe. The only replica here that uses that is the new Beck Super Coupe. Carey Hines (@chines1), the manufacturer, might be able to help you there. Is the fuel filler in the fender a requirement in the UK?