Depends whether you want to race on the circuits or on the small ovals. Don't know much about the circuit racing but checkout the previous mentioned website.
As far as the Oval Legends are concerned these are imported by Derek Hales. The championship is run by Mark Bond at Incarace. Mark organised a test a few years ago for me and I then agreed a drive with a team but was let down when the car was sold! Try either of these sites
www.incarace.co.uk or
www.oval-legends.co.uk