My bunny ate half a donut covered with chocolate while I was sleeping once. Just keep an eye on your bunny and make sure she eats a lot of hay. If she start to act differently take her to a veterinarian. Often it’s nothing dangerous, as long she didn’t consume a lot.
While quantity is important so is quality. Crap chocolate like a whole Aro bar isnt as bad compared to taking a tiny nibble of a dark chocolate Lindt bar.
Jasmine this isnt a wait and see what the internet says sort of thing. You need to phone a vet.
Years ago, my little girl got up in the morning before I did and fed one of my rabbits yogurt drops, and my rabbit died that night. I have no idea how many drops my rabbit ate. I think you should call a vet, especially if you are guessing at the amount eaten. In the USA, there is 24/7 Animal Poison Control Center (855)764-7661. Check and see if they have one in the UK.