Ok so not quite camping virgin but it's been a good 15 years.
How do I do it with a 15 month old? I'm going with my sister's family but they've got 2 DCs as well so I can't be a completely helpless numpty.
What should she sleep in (would normal grobag be enough?), what do I do about storing her milk/food, washing bottles etc? What do I do if she has a terrible night with teething? I can't imagine other campers would be thrilled hearing a baby crying all night.
In order... (I'm going to assume you are camping now-ish, weather-wise). Normal grobag should be okay especially if she is used to that, a 2.5 tog one paired either with a babygro/jamas and a warm comfy jumper (to keep her arms warm), OR a fleecy all in one instead of the babygro and then the grobag over that. Then just have a blanket to pull over her if she gets cold of a night. Storing milk and food can be a bit of a pain. If you google making a simple fridge you can do this, using a wet cloth, cold water and a few plastic boxes to create a makeshift cool area in the shade, the water constantly evaporating from the cloth draws heat away and keeps things cool <hazy memory> Err, anyway that might help. Can you buy ready made milk in little cartons if shes still on formula, or take UHT milk is she's on normal milk?
A tiny 1 burner camping stove is cheap and can heat water for washing bottles etc, though it's helpful to have a playpen/bumbo/travel cot/highchair to put baby in while you do this or it ends like a bit of a farce. Take a washing up bowl and it can double as a baby bath, table, and storage box. Or aforementioned fridge!
If she keeps other campers awake, just apologize and they will probably be fine, people forgive little ones a lot because they are so cute Consider pitching a little distance back from other tents, so they won't keep her awake if she goes down earlier than everyone else as much as anything.