If I had to go in, I'd treat it as a chance to fast! Or bring in some nut butter (unsweetened) to keep in my drawer. If your mum is up for it perhaps she could make you some 'fat bombs' for snacks e.g. roll coconut oil, nut butter with some coconut and cocoa. Lots of recipes out there but avoid the ones with dried fruit in.
Ultimately I guess you should try not to be stressed about something like toast given your lack of control over the NHS kitchens. It may be stressful enough being an in patient and having your routine disrupted and that stress increases blood glucose.
Hopefully this is a short term admission and you can regard any deviations from keto as an interesting experiment in what happens to your bg levels and insulin needs when you go off plan. I like the poetry idea (you can also listen to poetry on your phone if that's easier) as you walk around.
My best wishes to you and let us know how your are getting on!