Personally I wouldn't take a cat away in a caravan. However attached to you she might seem, she's probably even more attached to her familiar territory, and she'd most likely find the holiday quite traumatic.
It's probably worth checking out some local catteries. If it's a good one, they won't mind showing you round. Also, a good one will insist that your cat is up to date with all her injections and will ask to see the documentation.
But if she's in and out of the house, that suggests she has a cat flap. If so, asking your son to feed her would by far be the kindest option.