Just I had combined screening done yesterday. Hubbie and I had already decided we would not abort for Downs so for us it was about wanting to have all the info so we could be prepared.
How it changed the scan? Well initially it was much the same as the private scan - checking baby had a heartbeat, measuring length and agreed EDD.
Next they measured the fluid at the back of the baby's neck, crown measurement, checked for baby's hands, legs and for any obvious physical abnormalities.
After the scan, I then went for a blood test. The blood test, your risk factors (i.e. age, weight, etc) and using the measurements taken and blood test are used to calculate a 'risk' of DS and other chromosome disorders. They said they would get back to me with the results via mail within 7 days.
kitty best of luck with the scan! They need to bring your dates forward so we can be EDD buddies again. Not doing this labour thing on my own 
jazzy - from what I understand (from other threads) is that lightish bleeding is quite normal after sex. I would contact the midwife and get confirmation all is OK. Some links that may or may not be of help!:
www.babycenter.com/400_bleeding-after-sex-while-pregnant_3315763_190.bc
www.whattoexpect.com/pregnancy/symptoms-and-solutions/vaginal-spotting.aspx
acemay and bradders congratulations on your scans! Glad to hear they went well!
Fluffeh - Please do chase up on that - it's not acceptable not to have any notes by now or even any booking appointment done.
My booking appointment was around week 8-9 (I was given my pregnancy file, which all my notes in), my 12 week scan appointment card I received on week 11, yesterday was my scan and I have a 16 week appointment booked in with the same midwife. I can't imagine how they can do your scan without a booking appointment. Not to mention at your booking appointment you get blood tests done - which is another layer of screening for you and the baby. I don't see why you and i should have different experiences because you live in a different part of the country to me.
I would definitely chase the doctor's surgery and explain that your concerns and get chasing the midwife team - because the position they've put you in is unacceptable.