Rach,
I have been on both.
Primulut is used to bring on a bleed, without having to ovulate. It is like the morning after pill in smaller doses. Removes all the old lining to allow the clomid to work more effectively on a new endometriumn(lining)
Clomid is used to wake up the ovaries it promotes follicle growth and usually taken by people that have trouble ovulating. Although it also can promote more folicles on your ovaries rather than just the one or two that is produced during a "normal womens" cycle.
After you go back for a scan..the doctor will let you know if it is "safe" or need to increase your dosagecto bring up the dominant folicle. Safe is when there is no more than 2-3 dominant folicle as then you may risk a high multiple preg. You either then recieve FSH pee ticks to get ovulation day then either bd or IUI.
Anymore questions always happy to help.
As Angel said there are very well informed people in TTC and LTTTC that are always happy to answer anything. Hope your day has improved
Bec