I found the original text, from Crime and Punishment. The meaning is quite difficult and perhaps deliberately so. The speaker is said to be drunk and sometimes lose the thread of his sentences, which he may have done here. Or perhaps he means that he is preparing himself for the humiliation of beggary by drinking in that pot-house or tavern.

The important thing to know is the use, "hence the ..." Hence means "therefore." So, this is a common usage: I could say: 1) It is Halloween. Therefore, I am wearing a costume. OR 2) It is Halloween. Hence, I am wearing a costume. OR 3) It is Halloween. Hence, the costume. #3 is most often used in response to a question: Joe: "Why are you wearing a mask?" Mary: " It is Halloween. Hence, the costume." Or, even more commonly: Joe: "Why are you wearing a mask?" Mary: " It is Halloween." Joe: "Ah! Hence, the costume! (in other words, "I now understand that you are wearing a costume because it is Halloween"

never heard of it

https://www.thefreedictionary.com/pothouse This reference says that it is a historical British term. I had never heard it before and I am British.