The 33-year-old is due this week to start production on Molly, which follows the life of a single mum and her six-year-old daughter.
Katie, who is seeking sole custody of Suri, has co-written and is co-producing the movie.
It will be shooting until August in New York, where Katie has moved into a new apartment with her little girl.
The Dawson's Creek star is keeping busy with work in the wake of the split. After the summer she'll start filming romantic comedy Responsible Adults with Chace Crawford.
And she's also planning her first ever catwalk presentation at New York's Fashion Week for her clothing line, Holmes & Yang.
Katie and Tom's lawyers are said to be negotiating behind closed doors to reach a divorce settlement.
"Neither of them wants this to be hashed out in public," a source told US publication People.
Reports suggest the actress will appear in a Big Apple courtroom on July 17 to request temporary child support from her estranged husband.
It's not clear whether Tom – who has gone back to LA – will also be present, although it's thought legal team might request temporary visitation rights with Suri.
The couple's lawyers are said to be negotiating behind closed doors to reach a divorce settlement.
Tom doesn't want any public mud slinging or fights," a source tells HELLO! magazine.
"He has vowed to deal with this matter in a dignified and calm matter. He still cares for Katie and wants what's best for Suri.
"He still hopes she can let him have one more chance and wants to show Katie that they can make it together as a couple.
"It really is a challenge, but Tom doesn't want to lose Katie or Suri."
The Top Gun star isn't about to give up on his marriage without a fight.
"He will give her anything and will do anything to win her back."
For a special report on Hollywood's most talked-about divorce, pick up a copy of the current issue of HELLO! - issue 1234 - on sale now.