When a British recipe calls for using non-alcoholic ginger beer, what should I use? I'm assuming that something like Old Tyme Ginger Beer or something I can pick up in a Jamaican market would be correct. Is that right?
Yup, that's right. Old Tyme, (Jamaican) Barritt's, (Bermuda) D & G, (Jamaican) or Fentiman's, (Brit export) are some of the better ginger beers. I don't drink the stuff anymore, myself, as it gives me some mean agita.
British ginger beer is much more potent than Jamaican. To keep it authentic find yourself some Fentimans or for an extra kick some Golden Cockerel.