Ask an Immigration Solicitor. Get an Answer ASAP.
The reason your application failed is because under a visitors visa you are not allowed to study for more than 30 days an the course provider is not accreditated to take foreign students. So you need to find a provider accredited by the Home Office. You are not allowed to marry in the UK under a visitors visa too.
You have provided further information to help answer your question but at the same time, you have given a negative rating. Unless you are prepared to review your rating I wouldn't be assisting you further.
OK give me a minute
OK. It is important when making a visitors visa application that you can show good reasons why you would return back to your home country and not remain in the UK. For this reason, it is important you provide evidence of your marriage back home as proof that you have to leave the UK after your exams to attend in your marriage.
It is reasonable to cancel the course given that your visa has not yet been granted. You can make a fresh application immediately with all the relevant information.