Yes, because even the worst-stocked pubs would have at least a bitter and a lager. Then they could have cider or Guinness on tap (cider is also drunk by the pint here).

So just asking for a pint would be no good.

The exception would be if you are a regular in the pub and you always drink the same thing. Then the barman would probably know what you drank and sometimes you wouldn't even need to order - he would start pouring out your beer as soon as you walk in.