Milk products are good but you can get Calcium etc from Vegetables so if you want to be a vegetarian then go ahead. Get a blood test every 6 months to see if you have enough iron, Calcium and B vitamins.
Most Vegans are very healthy but need to take more care to eat well. I always start my day with a small bowl of cooked oats, use the “3 bears recipe”. 2 tablespoons per person of fine rolled oats, a cup of water and nothing else. bring to the boil and turn off the gas. cover and leave for 15 minutes.