SSEC is usually held in May and SSUK is usually held early September. As far as I know these will be when they are held next year.
Wheels size varied hugely at SSUK, skinny and fat 26 and 29'ers, 29 Plus seemed to be the chosen size but really there was everything you could think of, with quite a few 650b's running about. That's the cool thing, seeing what others are doing. I have never seen so many Stooges in the one place before and some were 29 and some were 650B plus, and when you see them side by side with a steel Jones then you can see the huge similarities.
The trick is to ride what you normally ride
There were quite a few V brakes as there was quite a few running 'traditional' 26'' wheeled mtb's. Weirdo's