Hi
I am currently working in sport and have been with a successful Rugby Union team. I would definatly advise getting yourself on a sports first aid course and make sure you can tape, as Ophqui has suggested. The RFU, like the FA, do have their own specific first aid course wich includes spinal care, log rolls etc, which some standard courses do not cover. Other than that your undergrad training will give you a good foundation, enjoy and learn along the way.
I guess on match days in the changing rooms at first it may be intimidating but trust me the players will treat you just the same as anyone else and you won't feel out of place.
Best of Luck