Saturday's New Shows

THAT'S LIFE
CONCEPT Instead of getting married, Lydia, a thirtysomething working-class New Jerseyite (Heather Paige Kent, of Jenny), dumps her loutish fiancé and goes to college. Ellen Burstyn and Paul Sorvino are her loving but apprehensive — okay, nudgy — parents.
THE SCOOP Based loosely on the life of creator and ex-waitress Diane Ruggiero, ''the script,'' Kent raves, ''was so good, so real and funny and sweet. We're following Lydia's journey, but it deals with family and friends and school, how she relates and interacts'' — especially with her most difficult professor, a snooty Englishman (Peter Firth).
BOTTOM LINE With Debi Mazar on board as one of Lydia's best friends, this hour-long drama could be what Martin Scorsese would do with a sitcom: Goodgals. Although, stuck on Saturdays at eight, it might have more in common with another Marty title: Bringing Out the Dead.