haven't read chrises link, but im sure its about how to make an NHS complaint. My advice would be to go down this route first, and the result of that will tell you how likely it would be that the hospital would be seen as at fault. if you are not happy with the outcome of their official complaints process, you can appeal to the health care comission. Then if you want to continue, consult a lawyer. if you use a lawyer during the other processes, they will not continue, as they are not allowed to, meaning its possibly costly for you, if you have no hope of winning.
Another thing to consider is that you will have to get your dads permission to persue this.