I've never sat on a jury myself, but have attended many hundreds of trials as a news reporter. That means a lot of hanging around the court lobbies, waiting for action in the courts. What I can tell you is that the only time you ever see the jury is when they are sitting in court. They are not allowed to be in the public areas including the canteen. Obviously, this is to prevent any communication with witnesses etc.
It is my understanding that they are waited on hand and foot by court clerks! I've never seen a juror arriving through the public doors either so I assume they have a private entrance. There are jury rooms somewhere in the private areas of the court building where they go while waiting for court to rise, during adjournments, lunch time etc. They are not shared with other juries each will have their own room.
They do definitely discuss the evidence during these times, which you can see from the number of times the Judge receives a message asking for clarification on evidence that has been heard.
If you remember, in Lit Up's brilliant description of court, it was described as being quite deserted (sorry can't remember the exact wording). There's a huge hive of activity going on in areas the public can't see. Court clerks and judges are all behind then scenes. You'd see barristers and solicitors a fair bit as they move between court rooms and other areas (there are interview rooms off the public areas where legal teams can meet with witnesses to discuss cases in private).