International student visa and additional learning

Hi, I have a question about study visas and additional courses. I'm in the UK on a study visa and I'm looking to enroll in a short term weekend vocational course so I contacted the center and they asked me if my study visa allows additional learning. I couldn't find anything about this on my visa or online so I figured it might be best to ask here. Does anyone know if additional courses are allowed on a student visa? Someone told me it shouldn't be a problem but I want to confirm if there are any weblinks talking about this.