I had grade 4 placenta praevia - first seen at 20 weeks when I was told "it will probably move", then at 36 weeks, it had got worse not better.
Had no bleeding at all, but an action plan in place at work, just in case, and went on maternity leave early and dossed about at home for about 7 weeks...
Had elective CS at 38+5. Baby had been transverse up to that point, which was probably why I didn't bleed, as no downward pressure on the placenta. Had a scan the morning of the CS and she had turned head down (which I felt her do the night before, and blimey, THAT was quite something!) so they whipped her out quick!
Haemorraged in theatre and lost 3.5 pints of blood - so they didn't drop the screen when my DD came out, which was a bit of a shame, but they thought I wouldn't want to see what must have been an unholy mess down there. What they didn't seem to have realised was the thing they were using to suction off the blood was draining into a tube which went past my ear, so I saw ALL of that blood dripping down anyway...I kept asking the anaesthetist "am I OK? am I OK?" and she was laughing at me which I didn't find very helpful...
So yes, another big vote of thanks to the blood donors out there from me!
DD is now 15 weeks and wholly unscathed... as am I now I have got over it. Would do it all over again in a heartbeat.
Very very good luck for a safe birth. Am sure you'll be fine though. All I would say is if you're not happy about having students in with you, SAY SO, because (due to the severity of the condition) it is quite rare and they do want people to have a look, iyswim, and I had a student anaesthetist and THREE house officers in with me, as well as all the other theatre staff and the whole thing was a bit claustrophobic to say the least.