While everyone is different, the usual reason people with dementia are fed up, or sad, or anxious, or bored, is because they have dementia rather than because of their surroundings. The wish to be somewhere else is a wish for things to be as they were before dementia. If you are still considering a holiday, before you attempt a long journey or a week away it would be good idea to do a trial run. Take her out for the day a couple of times, or away for a single night somewhere nearby, then you can see how she - and you - cope with it. You can gauge her reaction and her ability to enjoy a 'change of scene' and if it doesn't work out you would be able to get back to the CH promptly.