You could try going half a size down and for a G or wide fit in UK sizes. Some UK makers use their own sizing letters, usually F is standard and G is wide but see preceding statement.
Trace your foot - accurately - and send tracing and measurements plus volume measurement, to Herring and they'll tell you what is best.
You may still get it wrong.
Your best bet is to go into a shoe store thats sells UK shoes and try on and buy. Its not very complicated.
Yeah will do all I can at American Tailors and Double Monk; also traced my foot and compared it to the Meermin's I bought and they're just too damn wide for them T_T
Wish I had that Spoo narrow foot; also anyone know if losing enough weight can narrow your foot (my width seems to be fat) that will be all the determination I need to lose weight :)