People often ask me what to make a website and online business around 
I don’t usually have ideas as most of it is passion based (or should be).
But I have one today: pickleball! 
I see a tonne of American friends and people I follow talking about this. It’s huge right now and I can imagine it might take off in the UK, too.
Not a new sport (apparently created on an island off the coast of Seattle in 1965), but its popularity has grown hugely in last few years.
Also, Major League Pickleball (MLP) league just started. To join MLB, NFL, NBA, etc.
It’s like a cross between ping pong and tennis and seems like a good fit for all age groups. So huge audience!