What do you mean by septate hymen? Do you just mean a vaginal septum?
I had my septum removed a couple of months ago, I had bleeding for about a week after (similar amounts to a light period), but then I ended up having my actual period the week after.
I had what I thought was blood clotts coming out throughout this time but I determined with my gyno that it was remainding tissue left inside, my gyno had burnt through the septum and then cut it along the walls, and then stitched it up, so it was just small bits of tissue. Having my period afterwards helped actully clearing it all out and preventing infection!