Breech babies?

Hi all... Got a routine scan tomorrow as my baby is breech, I will be 36 +3 if still breech I'm opting for a c section I had a natural birth last time with first but it was a bad experience due to a fractured pelvis from a younger age. At what week do they give you a c section also I've been having routine scans due to my first born been born on the 10th centile but last measured ok I also have a placenta membranacea which is why they think my daughter was born on the small side. Think I'm just nervous about birth now and looking for people's stories. Thank you.