Do check with your vet. I had a vet tech come in for my group of kitties when I had to travel. That worked well, just as K&L said.

Also, there will be a list of pet sitters at your vet's. These people are licensed and bonded. Here in RI they also have to be licensed. Keeping multiple cats in your home is less expensive than boarding them. I had a great sitter for 4 years! They will insist on meeting with you and the cats in your home in advance. They will have a list of questions for you - vet's name and number, where you keep the food, litter and litter disposal, carrier. Where you will be and how to reach you. Which food to use, how often are treats OK to give, and so on. there is usually a set price per visit for 3 cats, with an "add on" price for more than 3.

A month is a LONG time. If you decide on this and leave them in their home, set a few clock radios to come on and play music - set them at different times, so it is not a silent house.

Many vets also offer boarding.

Good luck working on these arrangements!