Set the options to save until you delete, or to discard shows to free up space. If you have plenty of room available, the shows will wait for your return.
Tivo will keep a recording for as long as you keep it on the hard disk drive without deleting it or over dubbing the program. If you would like to go out of town and make sure your programs are being recorded and still saved on your Tivo device you will not have any problems.
It won't delete anything as long as there is available space on its hard drive. Once the space runs out it will record over the space occupied by suggestions first and then "keep with space available" second. Anything that is "keep until I delete" will never be recorded over.