You'll find a Chassis tag on it which should state the year somewhere, or at least a serial corresponding to the year.
If you're Kent based Adam, then you'll find Bayford etc will run C50's in the Bambino class. If you want to run some club races etc just double check the chassis once equipped with a C50 is to regs. The club races are run to comply with Motorsport UK regulations (MSA). You'll find the latest 2020 Gold Book (.PDF)
here, skip to page 7.
I do belive however the minimum free practice age at Bayford is 5 and race age is 6. However, please double check that as I could be wrong!