ATC are paid to provide pilots with a service, not the other way round. Always keep that in mind while you are learning and you will approach the problem of being unfamiliar with the RT and flying at the same time with more confidence.
My standard brief to students is to say if you are having a problem with any ATC officer say " My instructor told me to tell you, bolox". I have never had anybody do this but it introduces the student to being able to relax more on the radio.
One of the things not readily passed on by instructors is that you can talk normally just as you down the pub.
Saying on the RT for instance. I am in a red C152 around 2000 feet and I am lost and frightened isnt CAP 413 but I can assure you it will attract as much, if not more attention, then a word perfect CAP 413 call. If ATC want to know something they will ask you. Press the button, make your best effort and let the guy who is paid to provide the service ask the rest.