Awaiting knee replacement surgery

Hi, i have been reading the message boards and would like to hear from anyone who has had knee replacement or is waiting to have it done. I am really scared and dont know what to expect. I need both knees done but not at the same time. So if there is anyone out there who would like to share their thoughts that would be great also any tips e.t.c for recovery. Is the pain really bad when you come round from the surgery? I have no knee caps has anyone had a replacement having no knee caps does it make a difference? I am bone on bone at the moment and mobility and pain is not good.

Thanks for any help i would be very grateful;)