Hello Les,
I don`t know about a tuning night, but if you want to be involved in an afternoon of absolute top rate Bantam stuff then the place to be on Sunday 14th of January is the Avenue Pub, Bristol Road, Gloucester, the car park entrance is located just on Tuffley Avenue. A quick look on Google maps will show everything clearly.
You can look forward to conversation with a triple Bantam champion, the guy who made the engine, various Bantam and 50cc racers, race engine designers, frame and suspension experts and loads more fantastic stuff. It all begins at 12 noon and every one is welcome to participate in a low key, friendly get together!
Cheers, Trevor