Hi helenc!
If you're having a Pipelle biopsy, the process only takes a few minutes. A speculum is inserted into your vagina, the cervix is cleaned with an antiseptic solution and a numbing spray or other local anaesthetic may be applied to your cervix. A forceps-like instrument may be used to hold your cervix steady and you may feel some mild cramping when it's applied. I found this the most uncomfortable part of the process. The Pipelle (a thin, flexible suction curette used for minimally invasive tissue collection) is gently inserted through the cervix and into the uterus. The Pipelle is gently moved back and forth to obtain a sample which causes some cramping, but it only takes a minute. It's exactly the same pain as a period, because the pain is caused by the same muscles of the uterus contracting. It's a fast procedure and the discomfort doesn't last long.
I had a biopsy during a check-in visit due to continued spotting at 6 months. The doctor suggested we do it while I was there, so I didn't have any warning and didn't have any anticipatory anxiety. I also didn't haven't the benefit of any pain relievers before the procedure and I experienced only mild cramping. My doctor was very efficient and worked fast. I was on and off the table in a few minutes. Some vaginal spotting or bleeding is common following the procedure, so take a liner or pad to your appointment. Some women experience mild cramping in the following day or two. If you need a painkiller, you can use whatever you would normally use for period pains. I didn't need to take anything after the procedure and I was fine the next day.
Anxiety can heighten pain perception, so deep breaths and try to relax. I hope your procedure is as uncomplicated and minimally uncomfortable as mine was.