Thank you ladies. You both answered my question thoroughly!
For it to be a longer one, they measure just about everything. Your cervix, they will check for any abnormalities in your uterus, they will check the placenta. They measure babys head, belly, femur, bunch of organs, they will check babies heart, the umbilical cord, they need a lot of pictures. You won't really need to do much personally, but it's definitely a decent length, it can be even longer if baby isn't cooperating. You may be sore after depending on how baby is sitting. Any clinic I've been too for ultrasounds I've gotten to watch the whole thing, and gotten 3-4 pictures at the end. Was there anything specific you were wondering about?
If you haven't found out what your having then it will be your anatomy scan. Which will tell you whether it's a boy or girl. if you have had your anatomy scan then it is likely that you will only get to hear the heart beat today.