New US Trailer, poster and character posters

At the Fox website here (scroll down for the posters).

Music by Damon Albarn’s music collective Electric Wave Bureau

Can't find the original source for the information but no reason to doubt this from Film Music Reporter.

Damon Albarn’s music collective Electric Wave Bureau has composed the music for the upcoming fantasy adventure The Kid Who Would Be King.

New Official Poster

 Also confirming US and UK release dates:

The official poster for #KidWhoWouldBeKing, in theaters January 25. pic.twitter.com/kUAptNFRax

— The Kid Who Would Be King (@KidWouldBeKing) December 11, 2018

Here's the official poster for The #KidWhoWouldBeKing, in UK cinemas on 15 February 2019. pic.twitter.com/Vd6YHG5uGm

— Working Title (@Working_Title) December 11, 2018

Preview Screenings have begun

Had the great pleasure of seeing Joe Cornish new movie, #thekidwhowouldbeking, all finished. You guys are in for a treat next year. A rollicking adventure with a cast of new stars to be... V. proud of Joe and the team on this one. pic.twitter.com/EBTJ4Bl1MT

— edgarwright (@edgarwright) December 9, 2018

Last night I saw a private screening at @20thcenturyfox Studios of next years “The Kid Who Would be King”. Guys it’s SO SO Good!!!! If you like films like Harry Potter, Lord of the Rings & Chronicles of NARNIA, then you will LOVE ❤️ this one! @KidWouldBeKing #KidWhoWouldBeKing pic.twitter.com/fLPAc667Ds

— Lindalee Rose (@iamlindaleerose) December 8, 2018