So sorry you're having to go through this. I had 2 ERPCs earlier this year - no complications, but it turned out I had a molar pregnancy, so they had to remove some regrowth. All fine ever since.
The procedure itself was much more straightforward and stress-free than I had imagined. Went into hosp about 8 am - for the first ERPC I had a vaginal pessary inserted - had to stay in bed for about 30 mins after that - this opens the cervix. By the time it came for the procedure - about 11:30 - 12, I think, I had some crampy period-like pains, but nothing terribly uncomfortable.
Anaesthestist explained the GA procedure in anteroom - everyone very caring and calm. Was under for 20 mins, maybe - woken up after what felt like a very restful sleep. Back to room, slept for a while, then had lunch and DH and dd came to pick me up about 2pm. I was very tired the next day, and dozed on the sofa a lot - the day after we flew to Italy on holiday. Bleeding wasn't too bad, iirc, and I really don't remember any afterpain at all.
The whole experience was so stress-free that when I had the mole diagnosed and was called in at short notice for a second ERPC, I was positively chirpy, bizarrely enough. Our hosp is very good - there's an entirely separate ward for these procedures, though I did have the surgery itself on the labour ward - was wheeled through and didn't see or hear any pregnant women or new babies.
I hope tomorrow goes well - be gentle with yourself, and take it very easy in the days after the procedure.