No, you can't have a safe small kitchennette. As nothing is safe to certain residents, and anything may be safe for others.
Generally there is a trained kitchen staff or more than one in the kitchen at all times from 8 am to 8 pm. Residents may access the kitchen, however typically when they do, they are asked what they would like and if they need help. Their access is supervised. Details will vary depending on the size of the home.
From 8 pm to 8 am, generally kitchen access is limited because you may not have the same kitchen staff coverage.
Typically during those hours, the care staff will provide snacks on request, where reasonable to do so.
Residents are entitled to access the home like a home. Food stores with specialised fridges tend to be seperate rooms off the kitchens.
Fridges in the actual kitchen tend to store basics for use during that day, like milk and butter, maybe packaged ham slices, cheese, yogurts etc. If a resident enters the kitchen, they tend to be asked what would they like, and their request is responded to.