The Chessington Branch line runs between Motspur Park & Chessington South Motspur Park Malden Manor Tolworth Chessington North Chessington South the roling stock is the class 455 701 & 707 emu
Somebody is already working on a freeware version of this, but I agree that it would be nice to have something official to extend the PDL by DTG. Here's useful links to the WIP freeware stuff: https://www.facebook.com/groups/waterlooportsmouthmolevalleyextension
Great Route & I Hope it is an extension pack for the Portsmouth Direct line From London Waterloo to Portsmouth HBR