Hettie
Am also so sad to read your thread, and you news. I am not trying to be discouraging and know many people like "Onlyaphase" for whom it was over and done with within a few days and was like a heavy period. However to be realistic and help any decision making, here is my experience.
I had a similar timing to you, found out at 8 weeks after spotting that baby probably stopped developing at 6 weeks, and to expect miscarriage. 2 weeks later it all started and I spent 12 hours stuck in the bathroom with a friend and my mother outside loo door. I lost so much blood I was dizzy so got admitted to hospital. Was discharged from hospital the following morning (just in over night) as iron count OK. I made the decision to manage it naturally and to cut a long story short, three months later the bleeding stopped.
I didn't originally opt for a D&C because I wanted to go through process naturally... I had no idea how drawn out and disabling it would become. In the end I had drugs to help the womb contract and eventually booked in for a D&C only to find out there wasn't enough left and that is when it finished a few days later. But there was no telling when it was going to end.
If it happens again to me, and I hope and pray it doesn't, I do not know what decisions I would make, and I have no judgement on how others deal with it. I was an unusual case... the medics were flumuxed so it is unlikely that you will experience this... but it may not be like a heavy period like leaflets say, and you need to just take it a day at a time and insist on advice and scans and checks from the medics if your gut feeling wants reassurance.
I have to say, the first main day, despite being a hot summers day stuck in the bathroom, was manageable, unpleasant and sad, but manageable. The following three months were disabling and I didn't feel I could grieve until it was all over... and then most people had forgotten about it so I felt unsupported.
And it is a bereavement, but different people deal with grief different ways, so make sure you have the type and level of support you want and need around you.
There was light at the end of the tunnel for me though as I now have a gorgeous DD.
I wish you all the best, and hope all goes well, as painless as possible physically and emotionally and that you get good support and care at this time.