Don't worry about it, I think every area works slightly differently, but in any case your doctor will usually refer you to a midwife by sending a form to your local unit. Then it's generally up to the midwife to contact you and make an appointment. It can take a couple of weeks or more sometimes, just depends how many ladies they are looking after at any one time. Simoultaneously your scan date should be arranged so you may even receive contact from your midwife and scan unit around the same time. Having said that, obviously every doctors surgery work differently so if you are at all concerned then the best thing to do is contact them directly. The receptionist should be able to tell you how it works in your area without having to see the doc, remember they see hundreds of pregnant women each year so general routines are in place to follow.
In any case, I would expect a scan and m/w to see you before about 14 weeks unless there is a major back up. Don't worry, just relax and enjoy it! The later you have a scan the more you will be able to see anyway!!
Hope this helps. Lol Lisa x