They wont be looking for wit or individuality im sorry to say. Stability and trustworthiness will be desireable attributes in this case. You should be under no illusion that this student committee is nothing more than a scapegoat plan for when parents or students question the school's interest in their needs, and a concept that will look good to ofsted. And youre probably aware that a student committee will have practically no impact on decisions made by staff. Thats the case in my school anyway.
On the plus side, a seat on the committee will look (quite) good on a CV, so you might as well go for it.
I cant think of any specifics, but an anecdote is good way to start your statement. That way, the first sentace will be launching into a little story, and people will be intrigued to see what happens and how it is relevant to the point youre about to make. They'll just naturally read on.
People who use anecdotes in converstation are also seen as more interesting and articulate people, as it hints at experience and an ability to draw value from these experiences.