Rabbits do this. Contact the vet if you want investigations or you have other rabbits who you feel might be at risk. A vet might also have information about disposal, for example, some people have pets cremated and keep ashes and a vet's office will probably have the contacts for that.
About work - if you are fit to work, go. If, as it sounds, you are not fit, phone in sick. Don't tell them your animal has died, unless you know this will be well-received. I was a teacher, we weren't paid if we had days off for vet visits, sick animals, bereavements.
I am very sorry for your loss. Do check back as people more knowledgeable than myself will be along shortly.
eta: if you are going to work, can you place pepper's body safely and put her somewhere safe outdoors for now (a secure shed or garage? or in her hutch if she's an outdoor bun), as the deterioration of her body cells will cause an odour that will upset you and might linger.