Can i sue haven for son splitting his head open?

it was our first night at haven and we were walking to the entertainment hall, my son and daughter were skipping in front, suddenly he starts screaming he had fallen over a huge rock/boulder that was at edge of pavement, this boulder was totally in darkness and was barely visable, we picked him up and ran him to the reception where the staff called for a first aider, even though i demanded an ambulance. they then all disappeared, 5 mins later the first aider appeared, who was absolutely brilliant, but i could still see no sign of the ambulance, when i found a member of staff where the ambulance was they sais you will have to call for one yourself, a paramedic came out and glued my sons head up, this totally ruined his hol for him as he then couldnt swim, or join in the archery of football, does anyone know how i stand for possibly sueing? or should i just complain to the haven company?