Could anyone tell me how to go about expressing my interest in a research topic to a prospective supervisor. i don't know what to include in the email.

What's best is to explain about your degree, The degree studied, e.g. BSc-biology, grade (Or expected) modules of interest/relevance and what you did well in. You may want to include coursework titles and what is important is your final year project. Describe why you are interested in the area/project. I'd recommend writing a letter and sending it with a CV aswell, rather than just an email.