Please consider an extension lead, which will reach the bed from a plug socket in the room. Not all rooms have a socket nearby.
I have sleep apnoea, and usually take an extension lead with me - just in case there isn’t a plug socket near enough to plug in my cpap machine.
It’s potentially saved my life many a time. If I forget to pick up the extension lead I could be in real trouble.
Also, maybe a slimline or desk fan for those hotter days - or for ladies going through the menopause! 
Spare batteries for the TV remote.
The cottage we went to recently had a comments book where people left their reviews. It was lovely reading back through it, and seeing what others had said over the last few years. Pictures drawn from children who had stayed were lovely to look at too. You could feel their excitement of seeing the animals (goats, sheep, cows in nearby fields)
They also had a photo album showing how the property had been transformed from a barn to a cottage which was great to see.
An instructions notebook. Telling you where things are… eg: electricity box if the lights go out, water heater/immersion, and a list of emergency numbers - hospital, doctors/walk in clinic, chemist, dentist, vet.
Good luck in your venture ?