If you don't mind travelling, have a look at the occasional race in the Classic Sports Car Club's series'. They run 30 min practice and 40 min races to a "mini enduro" format, ie a compulsory pit stop, meaning races can be for one or two drivers. Good fun & good value per track minute, particularly if you can share costs ith a second driver.
I race either an Alfa 33 or a Fiat Uno in the Tin Tops series but there are also Alfas in the "Swinging Sixties" and "Future Classics" series, too.
Have a look here:
CSCC Home Page
Next race at Oulton Park on Aug 9th.
Rgds
Andy