According to the info from MAHQ.net, the specific timeline will be around UC0093, since it involves some MSs from Char's Counterattack, such as Jegan and Geara Doga. However, the fight is not between Londo Bell and Neo-Zeon, but a new organization called Sotsudeki. The long-haired-Char-look-alike on the homepage of the official website might be from that organization, and I bet he's playing the villain. :-)
MSs wise, like I said, too few images to decide whether I like the series or not. The only MS design available on the website is NZ-666 Kshatriya (how do you pronounce that?). Super-duper cool!!! It's like a mix of Gelgoog (the head) and Quin-Mantha from the ZZ era. All the Zeon ornament on the wrist and the on chest, and the green color scheme really reminds me of the old Principality. Might be a bit early, but I'm hoping that this fella will come out as a MG kit. 22.3 meter in height is quite close to match Sazabi.
NZ-666 Kshatriya - Image from MAHQ.net
By the way, the model number of NZ-666 is supposedly from the Newtype prototype MA series developed by the Neo-Zeon during Char's Counterattack era. MSs of the line include NZ-222 Psycho Doga and Quess Paraya's NZ-333 Alpha Azieru. So, I guess Kshatriya's concept is close to being a MA as well.
I hope to see more updates on Gundam Unicorn soon.