Indy to Leeds, huh - welcome to culture shock....
The good news is that in the UK, the cops don't drive their cruisers as family cars when they're off duty and there aren't so many of them on the roads. I don't think I've ever seen so many cop cars on the roads as I did in Indianapolis where a radar detector seems to be a must-have.
The bad news is the number of fixed speed cameras and camera vans in England. Also, I've always thought that there's something of a different approach to speed limits here in the UK with, arguably, a greater observance of them than anywhere I've been in the US.
Oh and you can't turn left on red here as you'd turn right on red in many US states. It is, however, legal to lane-split / filter / call it what you will in much the same way that you can in California. Covering big distances here in the UK will take you much longer than it will in the Mid-West. 300 miles is a long way in the UK and could easily take you 6 hours or more.
I can't really comment on local rides other than heading SW out of Leeds for 15 to 20 miles to the Peak District. Much of the rest of England is a wasteland when it comes to good motorcycling country. Wales can be nice and much of Scotland is superb, apart from the weather....
As for importing your bike from the US, the simplest and quite possibly the cheapest way to do it would be not to do it at all, sell yours in the US and buy a good used bike over here. You might want to research the respective values of used motorcycles on both sides of the Atlantic. However, if you really must import your bike then you might like to start your research here.....
https://www.gov.uk/importing-vehicles-into-the-uk
On reflection, perhaps it's not quite so bad as I might have made it sound....
HTH