Well, I think most of the recs I intend to give have a spoiler warning at the beginning - this one does, for instance. I think that's largely true if you start reading at the main Lost fic communities, as well. Other than that, I would say, read carefully :) I can try and work out spoiler warnings on the fics I'll recommend that don't have a warning, but it's tricky, I'm UK-based too, but I've been downloading them as I've been going along, and having seen it all, I might make a mistake. I'll try though! :)