Any advice would be welcomed.
The simplest advice would be: don't bother. The vast majority of the bars here which could sell that kind of product are tied to deals with Polish beer companies (or at least the Polish operations of international brewing groups) which prevent them from stocking any beer other than that produced by that company. I recently did some market research for a major international brewer which involved interviewing the managers of the 40 top bars in Warsaw (plus barmen and customers). Only three places were not tied to exclusive deals. And few places cared about beer, the profits are far better on wine and spirits.
If you buy the cider, I'd be happy to meet you at Bradleys and talk you through all of this.
