I agree with the other ladies it can vary where you are in the UK and your local PCT. I haven't had my booking appointment yet and I'm 9 weeks on Wednesday but so far there have been no signs of any problems so they aren't likely to see you before about 8 weeks round here (they lost my referral so that's why my booking in appointment is late).
Here you go to your GP who then refers you to the MWs at the hospital and you get a booking in appointment where they do all the weighing, measuring, taking family history, blood pressure and take both urine and blood samples to be tested. They also then give you the number to call to book your dating scan or nuchal scan (dating scan literally is just to date the pregnancy and check all is ok so far/how many babies, nuchal scan is the screening for Down's syndrome and other anomalies, you chose which of these you want). They are usually done around the 12 week mark. Then you go from there based on whether you are considered low risk or high risk (I am high risk due to previous c section less than a year ago as well as pre-eclampsia last time) and as a PP said if you are low risk you will be seen approx once a month til 3rd tri then more often. Plus the 20 week scan to check all organs etc are developing properly and if you are lucky to tell you the gender.
Hope that helps! My advice as it's your first pregnancy just go see your GP and they will tell you where to go from there Hun. Congratulations and h&h 9 months to you!