I found this radio advert on youtube to give me a general idea of what sort of thing I should be aiming for. All other types of radio adverts I could find on youtube were all quite similar.
I decided to try something new and original that I couldn't find other examples of, and decided to do a 30 second slot of a popular song which most people will have heard before, and write my advert script in a way that rhymes and fits the tempo of the song.