Try not to worry, Winnie. Easy to say, I know.
Plenty of people have laparoscopic ovary removal which is entirely uneventful. Mine certainly was, it was an absolute piece of cake. I was signed off work for a couple of weeks and quite frankly after about 3 days I felt like a complete fraud as I felt so well.
(I can't comment on how quickly any menopausal symptoms might kick in afterwards as my situation was complicated by other medication and medical treatment and the fact that I couldn't have HRT.)
Sorry to hear you haven't had an opportunity to speak to anyone about this. I see you have an appointment for a pre-op assessment. That should be your opportunity to ask as many questions as you need. Personally I always write a list of questions before appointments, make a copy and take someone with me to note down the answers and I don't leave the consulting room until I have all the answers. No medical professional should expect you to consent to a surgical procedure until you have enough information to make you feel comfortable to proceed.
Ask questions - it's your body, your future, you are in charge.