appointments on NHS??

hi, i was wondering how appointments are arranged on the NHS? like how often do you get ultrasounds? do you get an actual appointment every month? anything like this... i've been in America with my husband but since finding out im pregnant he decided he doesnt want to be with me anymore and im moving back home. my first appointment is on Friday and im having it here before i fly home so i know im probably going to need another 'first' appointment when i get a doctor back there... but im curious as to what happens through the NHS?