It's hard to feel confident when you haven't met the specialist. Planning and preparing to be in pain afterwards might not be a bad idea. At least then if it does happen it will be expected and you can go into management mode (I'm assuming you have lots of pain management experience BW) rather than it coming as a shock and then if you don't get pain, that's just a bonus!

They can definitely give you something for the anxiety on the day. When do you get to meet the specialist? I'm pretty sure they would consider it overkill to give you a GA for a biopsy. (I got mixed up earlier and it was the lung and chest lymph node biopsies that they wouldn't mildly sedate DP for (due to compromised breathing), not the liver one). But having said that, if you were to ask about it with the specialist, it might impress on them how anxious you are feeling about it.

medical procedures suck hun. I hope it goes well.