I did it at the Old Bailey, and it was a 2-week case where the defendant had pleaded guilty to manslaughter but the prosecution was going for murder. So the facts weren't in question, which made it simpler in one way. But some of the evidence was still pretty horrible to hear.
You have a clerk who herds you up and shepherds you around - at the OB there are so many courts it looks like loads of school trips being led around!
Our judge kept the sessions quite short (in answer to the pp worrying about toilet breaks). Sometimes it felt like they'd barely got started before it was time for another break, but it definitely helped me to concentrate.
If you are genuinely unclear on something and think it's important that you understand it, jurors can pass a note to the judge via the clerk, and he or she will either clarify or ask the appropriate barrister to do so.
The point about not researching the case is really important and was one of the things I found hardest, as a lot of my work has always been research.
It definitely felt like an important thing to do, and I was pleased and surprised by how seriously all my fellow jurors took it. When you're deliberating, the judge will send a clerk in after a period to find out if you are unanimous or if youthink unanimity may be reached. After a couple of rounds, the judge will indicate willingness to accept a majority verdict. I believe this has to be 11-1 or 10-2. I suspect our judge may have accepted earlier than some might because it was Friday afternoon!