When i go away from home for holidays i ask for a sitter, usually my parents or a neighbour. That way she stays in her known environment and (hopefully) feels okay, as opposed to be in an unknown place like a vet kennel. Make sure, if you can, to ask a sitter who has a thing for pets. One time a neighbour took care of her who was a very busy woman who had almost no time to look in and give her food and water, let alone spend some petting time with her. The pussycat was quite stressed when i returned. About the heat thing i can’t tell you much, just ask a (potential) sitter to do the same things while you are away, that you would do yourself to make sure that kitty is okay.