Given that I have no experience in purchasing or consuming liquor abroad, and don't particularly want to do so at this kind of place anyway, I could use some help.
A seedy pub in a rough equivalent to London. The kind of place that you'd advise a proper-looking woman not to go to, and where it'd be plausible to throw a chair or upend a table at someone if they pissed you off. Bar brawls every few days, lots of dock workers, sailors, and dirty laborers. You get respect if you throw a good punch or can hold alcohol well. Food's bad at best. This place does for some reason have a few foregin types of liquor, such as sake, in stock, but it's not particularly good. In fact, it's horribly bad. Let's call it a misdirected attempt at pleasing the Japanese sailors. I figure this is the kind of place where people go to drink beer because the beer's cheap as water, but anything else can be expensive, or the barkeep can jack up prices when he sees my MC clearly doesn't realize what kind of joint this is.
A price, in UK pounds, that the barkeep would charge for putting up a grimy half-full bottle of this nasty sake on the bar for my MC. It's not what she was asking for, but it's close enough for him to not understand the big deal. If you could tell me how likely it's for the barkeep to try and jack prices up because she's too polite to protest, that'd be nice, too.
A bonus if you could also give me a ballpark figure as to how much he'd charge her for a plate of disgustingly greasy fish-n-chips.
I have no idea how to find this kind of information online. It's not like a pub is going to ADVERTISE that it's shady.