I was told in the "UK nerdfighting party" forum that he's going to Edinburgh for a book festival on the 14th of August, and that he'll be visiting London sometime close to that date. I haven't found any further information, and I have no idea which date it will be... But "I've heard". :P
Aaargh. I wanna know the exact date, now! Bad John for not telling us when to travel to London aaall the way from Sweden to see him! (Ok, it's not that far... But the plane tickets still get more expensive every day.)
He did a live video stream and announced he would be in London on the 14th August and Edinburgh on the 15th, however those are the only places he is going because he doesn't want to be away from Henry for too long.
I think theres going to be a gathering beforehand and then we're all making our way down to Waterstones. I think everyone is still trying to sort out the details for that. Just keep checking the UK Nerdfighting Party group, that's where it's all being organised.