I would suggest attending matches etc as a fan and getting to know the players and the clubs you are interested in. Once you have some relationship they are more likely to welcome you as a volunteer. Be careful on the insurance side of things in terms of what you are covered for vs. what you are peddling. You are not yet a physiotherapist and so should not present yourself and your assistance as such. That may seem not important to an eager near graduate however one wrong step and an action by a player against you could end a career before it starts.