I went to Coventry a few times in the early to mid 80,s. Hednesford Hills in Cannock for the stock cars and bangers. Birmingham Wheels track sometimes. Still go to watch some races if in England at the time of the big races. The price of second hand cars may prevent banger racing.
The side stand problem shouldnt have happened , but at least Kawasaki replaced the frame. Good afte rsale service. Your CRF 250 will be fine , just tour at a lower speed. I would prefer that bike to a CB 500. Enjoy your tour.