ive been quite lucky, in primary school one of my teachers was a vegetarian so when the school had bbqs, fetes, camps etc she always knew what to feed me and helped my mum with ideas and nutrition.
high school was also generally good. i got given a bit of grief by people killing spiders and bees etc but my friends were really really supportive of my diet. the school was also considerate when it came to lunches/dinners/camps etc.
uni was fine as a vegetarian. people were generally open minded (not as much as in highschool and primary school, which is odd because i grew up in the country). i made the switch to veganism though and actually lost a few friends. i no longer get invited to as many social things and struggle to get anything to eat at on campus. i did a teaching round at a country school and was pleasantly surprised when the school was very supportive and inquisitive about my diet.
ive found that generally if you believe in what you are doing and are quite strong about it people will accept it. if they dont, then theyre great ones to remember why you are doing what you are doing - who would want to be like them?!

( i just had to add the beaver, hes awesome)