Many thanks to Keanuital for tweeting the link!
The BBC has posted that Keanu will appear on the Graham Norton show that airs on May 3, 2019. The show will air at 22:35 (10:35 pm) on BBC One. For those in the UK, the show will tape on Thursday night, May 2, 2019 and ticket info is here.
Note: Keanu will be in the UK on May 2, 2019. It is not clear if he will arrive a day earlier or how long he will be there. Regardless, if you are on the ground in London, please keep your eyes open for other talk shows that he may appear on. Any info that you can send to the site or tweet to the site would be much appreciated.