Wow to the video.
Logistics, logistics - maybe find someone in the U.K. that wants to buy bike that is located in the U.S. or advertise and sell one to someone in the U.K. Split the shipping with them with an agreement that you race it at Farleigh Castle. Race it, sell it, and fly back home. This way you only pay for 1/2 shipping one way and sell a bike to help pay expenses.
Another option like you mentioned before is to let a racer from the U.K. ride your bike at Unadilla and then have them return the favor at Farleigh Castle.
Or rent a bike.
I'd think one of the most expensive options along with customs complexity might be to ship a bike to the race, race it, and ship it back home.